ALBERT

Beschreibung:    We present a combined experimental and theoretical study to investigate the spatial distribution of photoelectrons emitted from silver-coated polystyrene nanoparticles. We use two-photon photoemission electron microscopy (2P-PEEM) to image electron emission from a silver-capped aggregate trimer. Finite difference time domain (FDTD) simulations are performed to model the intensity distributions of the electromagnetic near fields resulting from femtosecond laser excitation of localized surface plasmon oscillations in the trimer structure. We demonstrate that the predicted FDTD near-field intensity distribution reproduces the 2P-PEEM photoemission pattern. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7316-5 Authors Samuel J. Peppernick, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA Alan G. Joly, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA Kenneth M. Beck, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA Wayne P. Hess, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA Jinyong Wang, Department of Chemistry and Center for Nanostructured Electronic Materials, University of Florida, Gainesville, FL 32611, USA Yi-Chung Wang, Department of Chemistry and Center for Nanostructured Electronic Materials, University of Florida, Gainesville, FL 32611, USA W. David Wei, Department of Chemistry and Center for Nanostructured Electronic Materials, University of Florida, Gainesville, FL 32611, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Bi 3.95 Er 0.05 Ti 3 O 12 (BErT) thin films were prepared on Pt/Ti/SiO 2 /Si and indium-tin-oxide (ITO)-coated glass substrates at room temperature by pulsed laser deposition. These thin films were amorphous with uniform thickness. Excellent dielectric characteristics have been confirmed. The amorphous BErT thin films deposited on the Pt/Ti/SiO 2 /Si and ITO-coated glass substrates exhibited almost the same dielectric constant of 52 with a low dielectric loss of less than 0.02 at 1 kHz. Meanwhile, the dielectric properties of the thin films had an excellent bias voltage stability and thermal stability. The amorphous BErT thin films might have potential applications in microelectronic and optoelectronic devices. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7326-3 Authors Zhong Mo, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 China Xinrui Miao, College of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640 China Lirong Liang, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 China Wenli Deng, College of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640 China Baojun Li, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 China Dinghua Bao, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Copper oxide nanoparticles produced in double distilled water at room temperature by laser ablation of the Cu target have been investigated using TEM, SEM, AFM, X-ray diffraction, photo-spectrometry and PIXE. Q-switched Nd:YAG laser operating at 1064 nm with a pulse duration of 5–6 ns was used to conduct the experiments in the fluence range of 5.73–9.87 J/cm 2 . In each experiment, 12,000 laser pulses were used to ablate the target placed in double distilled water. Different diagnostic techniques reveal that the nanoparticles have a size between 2–55 nm and their mean size as well as the width of particle distribution increases with the laser fluence. Since no surface active material (surfactant) was added to water, the nanoparticles aggregated and settled down at the bottom of the container within a week. In addition to stable Cu 2 O, the XRD spectrum also shows the presence of suboxide Cu 64 O in the colloidal solution of nanoparticles produced in the present study. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7329-0 Authors N. Haram, Laser Lab, Centre for Advanced Studies in Physics, GC University, Lahore, 54000 Lahore, Pakistan N. Ahmad, Laser Lab, Centre for Advanced Studies in Physics, GC University, Lahore, 54000 Lahore, Pakistan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    To study the interactions between picosecond soft x-ray laser (SXRL) beams and material surfaces, gold (Au), copper (Cu), and silicon (Si) surfaces were irradiated with SXRL pulses having a wavelength of 13.9 nm and a duration of ∼7 ps. Following irradiation, the surfaces of the substrates were observed using a scanning electron microscope and an atomic force microscope. With single pulse irradiation, ripple-like structures were formed on the Au and Cu surfaces. These structures were different from previously investigated conical structures formed on an Al surface. In addition, it was confirmed that the development of modified structures, i.e., growth of hillocks on the Au and Cu surfaces, was observed after multiple SXRL pulse exposures. However, on the Si surface, deep holes that seemed to be melted structures induced by the accumulation of multiple pulses of irradiations were found. Therefore, it was concluded that SXRL beam irradiation of various material surfaces causes different types of surface modifications, and the changes in the surface behaviors are attributed to the differences in the elemental properties, such as the attenuation length of x-ray photons. Content Type Journal Article Pages 1-10 DOI 10.1007/s00339-012-7100-6 Authors Masahiko Ishino, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Anatoly Y. Faenov, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Momoko Tanaka, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Satoshi Tamotsu, Division of Natural Sciences, Faculty, Nara Women’s University, Nara, 630-8506 Japan Noboru Hasegawa, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Masaharu Nishikino, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Tatiana A. Pikuz, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Takeshi Kaihori, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Tetsuya Kawachi, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto, 619-0215 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    A theoretical study of the time-of-flight (TOF) distributions under pulsed laser ablation has been performed. 2D simulations of pulsed evaporation of atoms into vacuum on the base of the direct simulation Monte Carlo (DSMC) method have been carried out. It is found that for large evaporating spots (when the spot radius exceeds the initial plume length by a factor of five) the TOF distributions practically do not change with the spot radius variation. Moreover, it is shown that such distributions can be obtained from 1D calculations. Thus, in the frames of 1D approach, the TOF distribution is a function only of the number of the evaporated monolayers, but not of the spot radius. The shape of the TOF distribution is shown to strongly depend on the amount of the evaporated matter. Based on the calculated TOF distributions, dependence of the particle kinetic energy on the number of the evaporated monolayers has been obtained. To verify the theoretical results, experimental data on laser ablation of niobium and mercury have been used, which confirm the obtained dependences. The obtained results allow estimating the irradiated surface temperature from the TOF distributions for monatomic neutral gas. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7325-4 Authors Alexey A. Morozov, Institute of Thermophysics SB RAS, 1 Lavrentyev Ave., 630090 Novosibirsk, Russia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Developing a reliable and efficient fabrication method for phase-transition thin-film technology is critical for electronic and photonic applications. We demonstrate a novel method for fabricating polycrystalline, switchable vanadium dioxide thin films on glass and silicon substrates and show that the optical switching contrast is not strongly affected by post-processing annealing times. The method relies on electron-beam evaporation of a nominally stoichiometric powder, followed by fast annealing. As a result of the short annealing procedure we demonstrate that films deposited on silicon substrates appear to be smoother, in comparison to pulsed laser deposition and sputtering. However, optical performance of e-beam evaporated film on silicon is affected by annealing time, in contrast to glass. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7324-5 Authors R. E. Marvel, Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN 37234-0106, USA K. Appavoo, Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN 37234-0106, USA B. K. Choi, Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA J. Nag, Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235-1807, USA R. F. Haglund Jr., Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN 37234-0106, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Experimental results on picosecond laser processing of aluminum, nickel, stainless steel, molybdenum, and tungsten are described. Hole drilling is employed for comparative analysis of processing rates in an air environment. Drilling rates are measured over a wide range of laser fluences (0.05–20 J/cm 2 ). Experiments with picosecond pulses at 355 nm are carried out for all five metals and in addition at 532 nm, and 1064 nm for nickel. A comparison of drilling rate with 6-ps and 6-ns pulses at 355 nm is performed. The dependence of drilling rate on laser fluence measured with picosecond pulses demonstrates two logarithmic regimes for all five metals. To determine the transition from one regime to another, a critical fluence is measured and correlated with the thermal properties of the metals. The logarithmic regime at high-fluence range with UV picosecond pulses is reported for the first time. The energy efficiency of material removal for the different regimes is evaluated. The results demonstrate that UV picosecond pulses can provide comparable quality and higher processing rate compared with literature data on ablation with near-IR femtosecond lasers. A significant contribution of two-photon absorption to the ablation process is suggested to explain high processing rate with powerful UV picosecond pulses. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6910-x Authors Alex Spiro, Passat, Inc., 1124 Kingsbury Rd., Owings Mills, MD 21117, USA Mary Lowe, Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210, USA Guerman Pasmanik, Passat, Inc., 1124 Kingsbury Rd., Owings Mills, MD 21117, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The amorphous gallium nitride thin films doped with Mn were deposited by Laser assisted Molecular Beam Epitaxy (LMBE). After annealing at different NH 3 flow rates, the high-quality GaMnN crystalline films with different concentration of nitrogen vacancies ( V N ) were obtained, which were confirmed by the X-ray diffraction spectroscopy and Raman measurements. The magnetic behaviors of these films were also obtained to investigate the effects of nitrogen vacancies. It indicates that V N play a significant role in the origin of ferromagnetism. The stronger room-temperature ferromagnetism is given with the higher V N concentration when it is not beyond a critical concentration. Moreover, from our  M ( T ) curves and Raman analysis, the films present high resistivity. The magnetism of films with high resistivity varies with concentration of nitrogen vacancies, which can be explained by the bound magnetic polarons (BMP) theory. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-6900-z Authors B. Hu, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China B. Y. Man, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China M. Liu, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China C. Yang, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China C. S. Chen, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China X. G. Gao, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China S. C. Xu, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China C. C. Wang, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China Z. C. Sun, College of Physics and Electronics, Shandong Normal University, Jinan, 250014 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The sonochemical process drives chemical reactions with sound fields by creating extraordinarily high density of energy, pressure and temperatures. The process resulted in a number of unexpected chemical species and thought-provoking results in the recent past. In this paper, we present a new sonochemical approach to synthesize ZnO (zinc oxide) nanowalls (NWalls) on aluminum and alumina coated substrates at room ambient conditions. We achieved highly dense and uniform ZnO NWalls in areas that are coated with Al or Al 2 O 3 (alumina). The synthesis process was shown not to occur on Si, SiO 2 , Cr, or Ag surfaces. A series of experiments on understanding the growth kinetics offers detailed insight into the growth dynamics over time. Photoluminescence (PL) measurements, UV Vis spectroscopy, and SEM-EDS results confirm NWalls composed of crystalline ZnO that are formed via Al assisted growth induced by phase transformations under extraordinary pressure, temperature, and chemical growth kinetics. The chemical growth method as reported here, is applicable to arbitrary substrates coated with an Al thin film. We demonstrate the applications of the as-formed NWalls in UV photoconductors and gas sensors. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-6823-8 Authors Avinash P. Nayak, Department of Electrical and Computer Engineering, University of California Davis, Davis, 95616 USA Aaron M. Katzenmeyer, Department of Electrical and Computer Engineering, University of California Davis, Davis, 95616 USA Yasuhiro Gosho, Yamatake Corporation and BSAC Berkley, Kanagawa, Japan Bayram Tekin, Department of Physics, Middle East Technical University, Ankara, 06531 Turkey M. Saif Islam, Department of Electrical and Computer Engineering, University of California Davis, Davis, 95616 USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Novel urchin-like CdS was synthesized via a facile solvothermal route without any assistant agent. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, high-resolution transmission electron, and photoluminescence spectrophotometer. Based on time-resolved experiments, a possible growth mechanism of 3D urchin-like CdS microspheres was initially proposed. Furthermore, morphology control of CdS was achieved by adjusting the quantity addition of TGA to obtain the 1D CdS nanowires. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-6908-4 Authors Weiwei Cao, College of Materials Science and Engineering, Tian Jin Polytechnic University, Tianjin, 300387 P. R. China Hongde Gai, Shandong Special Equipment Inspection and Research Academy, Jinan, 250013 P. R. China Bo Zhu, College of Materials Science and Engineering, Shandong University, Jinan, 250061 P. R. China Yimin Wu, Zhejiang Cathay Packing & Sealing Co., Ltd., Hangzhou, 311255 P. R. China Chunlei Zhang, Guangdong Electric Power Research Institute of China Southern Power Grid, Guangzhou, 510080 P. R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The influence of the local crystallographic orientation of the polycrystalline bottom platinum electrode on the crystallization of niobium pentoxide thin films during their rapid thermal annealing was investigated by X-ray diffraction, X-ray reflectivity and transmission electron microscopy. The Nb 2 O 5 thin films under study were reactively sputtered in a mixed O 2 /Ar atmosphere and subsequently subjected to the annealing in argon atmosphere at temperatures ranging from 500  ∘ C to 700  ∘ C. The X-ray diffraction confirmed a transition from the amorphous niobium oxide to the crystalline orthorhombic Nb 2 O 5 for temperatures between 500  ∘ C and 600  ∘ C. The X-ray reflectivity measurements showed that the crystallization process was accompanied by a continuous increase of the electron density in Nb 2 O 5 and by a rapid increase of the surface roughness at 700  ∘ C. It was further observed by transmission electron microscopy that Nb 2 O 5 crystallizes selectively and that the crystalline domains of Nb 2 O 5 possess a strong orientation relationship to the platinum from the bottom electrode. The orientation relationship was identified as the most beneficial one for crystallization of Nb 2 O 5 . Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-6905-7 Authors L. Berger, Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg, Germany H. Mähne, NaMLab gGmbH, 01187 Dresden, Germany V. Klemm, Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg, Germany A. Leuteritz, Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg, Germany T. Mikolajick, NaMLab gGmbH, 01187 Dresden, Germany D. Rafaja, Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Singly distributed YBO 3 :Eu nanofibers with an average diameter of around 120 nm were fabricated using the electrospinning technique and characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The luminescent properties of the YBO 3 :Eu nanofibers were studied relative to the corresponding bulk material. The location of the charge transfer band in the excitation spectra shows a slight blueshift in the nanofibers compared with the bulk material. In the emission spectra, the ratio of the red emission at 611 nm to the orange emission at 591 nm (R/O value) in the nanofibers increased slightly, in contrast to the bulk, indicating that improved chromaticity can be obtained from YBO 3 :Eu nanofibers. The high color-rendering index obtained from them implies that these novel luminescent fibers can be used as potential candidates for nanodevices. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-6878-6 Authors Hongquan Yu, College of Environmental and Chemical Engineering, Dalian Jiaotong University, No. 794, Huanghe Road, Dalian, 116028 People’s Republic of China Hongdan Wang, College of Environmental and Chemical Engineering, Dalian Jiaotong University, No. 794, Huanghe Road, Dalian, 116028 People’s Republic of China Tao Li, College of Environmental and Chemical Engineering, Dalian Jiaotong University, No. 794, Huanghe Road, Dalian, 116028 People’s Republic of China Ruxi Che, College of Environmental and Chemical Engineering, Dalian Jiaotong University, No. 794, Huanghe Road, Dalian, 116028 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Controlling laser-pulse parameters is an important issue in pulsed laser deposition (PLD). In particular, homogenization of laser beams improves the reproducibility of the PLD process by guaranteeing a uniform intensity distribution and a well-defined energy density of the laser spot on the target. We have integrated a beam-homogenization system into our PLD setup, and here we discuss the results and advantages of using such a system. The optical setup is based on diffractive beam-splitter gratings, which produce a 2×2-mm 2 flat-top distribution with fluences of the order of 3 J/cm 2 on the target. We demonstrate the applicability of this technique by depositing thin films of ferromagnetic Ni–Mn–Ga shape-memory alloys. Magnetic and structural characterization, including secondary ion mass spectrometry (SIMS), indicate that nearly stoichiometric composition and crystallization in the desired martensitic phase is obtained for films deposited on Al 2 O 3 under optimal conditions. In contrast, the formation of silicide compounds at temperatures above 500  ∘ C is detrimental in the deposition of Ni–Mn–Ga films directly on silicon. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6904-8 Authors V. Kekkonen, Department of Applied Physics, Aalto University, P.O. Box 15100, 00076 Aalto, Espoo, Finland A. Hakola, VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Espoo, Finland J. Likonen, VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Espoo, Finland Y. Ge, Department of Materials Science and Engineering, Aalto University, P.O. Box 16200, 00076 Aalto, Espoo, Finland T. Kajava, Department of Applied Physics, Aalto University, P.O. Box 15100, 00076 Aalto, Espoo, Finland Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Tungsten oxide nanoparticles were fabricated by a pulsed laser ablation method in deionized water using the first harmonic of a Nd:YAG laser ( λ =1064 nm) at three different laser pulse energies (E1 =160, E2 =370 and E3 =500 mJ/pulse), respectively. The aim is to investigate the effect of laser pulse energy on the size distribution and gasochromic property of colloidal nanoparticles. The products were characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. The results indicated that WO 3 nanoparticles were formed. After ablation, a 0.2 g/l PdCl 2 solution was added to activate the solution against hydrogen gas. In this process Pd 2+ ions were reduced to deposit fine metallic Pd particles on the surface of tungsten oxide nanoparticles. The gasochromic response was measured by H 2 and O 2 gases bubbling into the produced colloidal Pd–WO 3 . The results indicate that the number of unreduced ions (Pd 2+ ) decreases with increasing laser pulse energy; therefore, for colloidal nanoparticles synthesized at the highest laser pulse energy approximately all Pd 2+ ions have been reduced. Hence, the gasochromic response for this sample is nearly reversible in all cycles, whereas those due to other samples are not reversible in the first cycle. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-6899-1 Authors N. Tahmasebi Garavand, Department of Physics, Sharif University of Technology, Tehran, 11155-9161 Iran S. M. Mahdavi, Department of Physics, Sharif University of Technology, Tehran, 11155-9161 Iran A. Iraji zad, Department of Physics, Sharif University of Technology, Tehran, 11155-9161 Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Microwave absorbing materials composed of ordered mesoporous carbon (OMC) as absorbent and paraffin as matrix were prepared, and their electromagnetic and microwave absorbing properties could be tuned by changing the weight fraction of OMC at 2–18 GHz. The minimum reflection loss ( RL ) value reached −9.3 dB at 8.0 GHz and the absorption range with RL lower than −5 dB was obtained at 5.8–14.4 GHz for a single-layer absorber filled with 1.98 wt.% OMC at 3.0 mm. If a double-layer structure was adopted, the total thickness of the absorber could be reduced below 2.0 mm and the effective absorption range ( RL 〈−10 dB) could be obtained at 8.9–14.3 GHz with a minimal RL of −28.5 dB at 10.6 GHz. This work demonstrated that dielectric composites could be used as excellent absorbers by adopting reasonable multilayer structures. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6906-6 Authors Hongjing Wu, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 P.R. China Liuding Wang, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 P.R. China Shaoli Guo, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 P.R. China Zhongyuan Shen, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Three-dimensional molecular dynamics simulations using the Tersoff potential are conducted to investigate the nanoindentation process of monocrystalline germanium (Ge). It is found that a phase transformation from fourfold-coordinated diamond cubic phase (Ge-I) to sixfold-coordinated β -tin phase (Ge-II) occurs during the nanoindentation process. The simulation results suggest that a pressure-induced phase transformation instead of dislocation-assisted plasticity is the dominant deformation mechanism of monocrystalline Ge thin films during the nanoindentation process. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-6901-y Authors P. Z. Zhu, State Key Laboratory of Precision Measuring Technology and Instruments, Centre of MicroNano Manufacturing Technology, Tianjin University, Tianjin, 300072 China F. Z. Fang, State Key Laboratory of Precision Measuring Technology and Instruments, Centre of MicroNano Manufacturing Technology, Tianjin University, Tianjin, 300072 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Dielectric relaxations and electrical responses in NaCu 3 Ti 3 TaO 12 ceramics were investigated as a function of temperature. NaCu 3 Ti 3 TaO 12 ceramics exhibit giant dielectric constants with values of ε ′∼1.45–2.08×10 4 . Two sets of thermally activated dielectric relaxations were observed in low and high temperature ranges. Sintering conditions have an insignificant influence on the microstructure of NaCu 3 Ti 3 TaO 12 ceramics, and have a slight impact on their ε ′ values. Thermally activated electrical responses of grains and grain boundaries have been studied at different temperatures by using complex admittance and impedance spectroscopy analyses, respectively. The low temperature relaxation mechanism is found to correlate closely with electrical response of semiconducting grains; whereas the apparent high ε ′ values are attributed to electrical response of insulating grain boundaries. These results support the internal barrier layer capacitor model to explain the giant dielectric properties of NaCu 3 Ti 3 TaO 12 ceramics. Additionally, high temperature relaxation may be attributed to the sample-electrode effect and/or defect ordering. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6897-3 Authors Nuchjarin Sangwong, Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 Thailand Weeraya Somphan, Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 Thailand Prasit Thongbai, Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen, 40002 Thailand Teerapon Yamwong, National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, 12120 Thailand Santi Meansiri, School of Physics, Institute of Science, Suranaree University, Nakhon Ratchasima, 30000 Thailand Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Here, we report on how the energy band diagram of a nanostructured semiconductor- metal interface aligns in accordance with semiconductor morphology. Electrochemically, titanium metal is anodized to form titanium dioxide nanotubes, which forms a junction with the free Ti substrate and this junction forms a natural Schottky barrier. With reduced dimensionality of the nanotube structures (lower wall thickness), we have observed band edge movements and band gap quantum confinement effects and lowering of the Schottky barrier. These results were corroborated with the help of cyclic voltammetry, ultraviolet-visible spectrometry, and impedance analysis. Current voltage analysis of the Schottky barrier showed a lowering of the barrier (by 25 %) with reducing dimensionality of the nanotube structures. At externally applied voltages higher than the Schottky barrier, charges can travel along the nanotubes and reside at an interface between the nanotubes and a high- κ dielectric. This property was utilized to develop high surface area solid-state capacitors. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-6898-2 Authors P. A. Mini, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India Alex Sherine, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India K. T. Shalumon, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India Avinash Balakrishnan, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India S. V. Nair, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India K. R. V. Subramanian, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham (University), Kochi, 682 041 India Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    CaCu 3 Ti 4 O 12 (CCTO)–silicone resin composites with various CCTO volume fractions were prepared. Relatively high dielectric constant ( ε =119) and low loss (tan δ =0.35) of the composites with CCTO volume fraction of 0.9 were observed. Two theoretical models were employed to predict the dielectric constant of these composites; the dielectric constant obtained via the Maxwell–Garnett model was in close agreement with the experimental data. The dielectric constant of CCTO–silicone resin composites showed a weak frequency dependence at the measuring frequency range and the loss tangent apparently decreases with increase in frequency. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-6885-7 Authors Sanjesh Babu, Department of Applied Sciences, IET, Mangalayatan University, Beswan, Aligarh, 202145 U.P., India Kirti Singh, Department of Physics, M.M.H. College, Ghaziabad, U.P., India Anil Govindan, Department of Physics, M.M.H. College, Ghaziabad, U.P., India Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Uniform arrays of silicon (Si), gallium arsenide (GaAs) and zinc oxide (ZnO) nanodots have been deposited using Pulsed Laser Deposition (PLD) technique combined with a contact mask consisting of nano-holes fabricated by E-beam lithography (EBL). These nanocrystalline semiconductor nanodots have been deposited by PLD on Si and GaAs substrates at room temperature. Characterization of the nanodots has been carried out using different techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Auger Electron Spectroscopy (AES), and Raman spectroscopy. This work demonstrates a novel technique for deposition of uniform array of semiconductor nanostructures using a contact mask at room temperature for photonic applications. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7158-1 Authors Manisha Gupta, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Vincent Sauer, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Ying Yin Tsui, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this paper, we present buried waveguides fabricated by fs laser writing in Nd 3+ doped YLF crystal under double line approach (Miura et al. in Appl. Phys. Lett. 71:3329–3331, 1997 ). The waveguides were made by focusing two consecutive optical breakdown tracks (OBT) separated by about 20 μm. To make the optimal OBT, we focused the fs-laser pulses 200 μm below surface at intensities above the OB threshold for the material and controlled the writing speed. The guiding structures were fabricated by using a Chirped Pulse Amplification (CPA) femtosecond (fs) laser system. We chose the optimal writing parameters in order to obtain suitable waveguides, using around 3 μJ energy and writing speed from 15 to 50 μm/s. After optically exploring the waveguides by end-fire coupling, the guiding structures showed good optical performance. Guiding index profiles were retrieved from modal analysis by using BeamProp (RSoft) commercial software. This spatial distribution of the index increment, taking into account a lower refractive barrier on the OBT region plus the compressed region between the tracks, was obtained correctly fitting profiles modes. Finally, optical spectroscopy measurements were also performed in the waveguides. The results showed that the luminescence properties of Nd 3+ ions are preserved in the waveguides compared with the values obtained for bulk. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7133-x Authors D. Biasetti, Centro de Investigaciones Ópticas CONICET La Plata-CIC, Camino Centenario y 506, MB Gonnet (1897), Pcia. Bs. As., Argentina E. Neyra, Centro de Investigaciones Ópticas CONICET La Plata-CIC, Camino Centenario y 506, MB Gonnet (1897), Pcia. Bs. As., Argentina J. R. Vázquez de Aldana, CLPU and Servicio Láser de la Universidad de Salamanca, Plaza de la Merced s/n, 35008 Salamanca, Spain L. Roso, CLPU and Servicio Láser de la Universidad de Salamanca, Plaza de la Merced s/n, 35008 Salamanca, Spain G. A. Torchia, Centro de Investigaciones Ópticas CONICET La Plata-CIC, Camino Centenario y 506, MB Gonnet (1897), Pcia. Bs. As., Argentina Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) in an orthogonal configuration was used to investigate plasma temperature and electron density effects on Mg II emission spectral line broadening. The experiments were carried out with two Nd:YAG lasers, one operating at 355 nm for ablation and the other one at 1064 nm for plasma reheating in air at atmospheric pressure. Temporally resolved plasma temperature and electron density were measured at various delay times. Data in this study show prolonged emission of Mg II (280.27 nm) as well as enhancement of the signal intensity when using double-pulse excitation compared to the single-pulse case. An enhancement of ∼8× was attained with a delay between the laser pulses equal to 1 μs. The enhancement was accompanied by higher plasma temperature and increased electron density. The double-pulse LIBS configuration provides energy to sustain the plasma emission at a period in time when the linewidth is minimum, thereby improving the analytical capabilities of low spectral resolution instrumentation typically used in LIBS system. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7153-6 Authors Inhee Choi, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Xianglei Mao, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA J. Jhanis Gonzalez, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Richard E. Russo, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this paper we present the development of an open code (“MATFESA”) based on the Finite Element Method (FEM) which can be used to estimate the strain and refractive index fields after femtosecond laser writing process by means of an iterative analysis. The fs-laser pulse residual stress control is the key to obtain high performance guiding structures for photonics. The whole complex physical problem consists in almost three steps inside the material during/after femtosecond laser interaction which cannot be analyzed using thermodynamic equilibrium equations. These are: ionization, expansion and re-solidification. In the numerical model solved, a mechanical expansion is introduced in the focal plane to simulate laser interaction at intensities above the optical breakdown threshold. Numerical results were compared to experimental measurements of optical guided modes in LiNbO 3 fs-waveguides. The MATFESA model was compared with ABAQUS commercial software in order to verify the strain field results and also to test the 2D, plane strain approximation. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7132-y Authors M. Tejerina, Centro de Investigaciones Ópticas CONICET La Plata-CIC, CC nº3 M.B. Gonnet (1897), Pcia. Bs. As., Argentina G. A. Torchia, Centro de Investigaciones Ópticas CONICET La Plata-CIC, CC nº3 M.B. Gonnet (1897), Pcia. Bs. As., Argentina Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO 2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with Cu  K α ( λ =1.5405 Å) radiation. The diffraction patterns were recorded in the 2 θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser-modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7149-2 Authors S. N. Aqida, Faculty of Mechanical Engineering, Universiti Malaysia Pahang, 26600 Pekan, Pahang, Malaysia D. Brabazon, Materials Processing Research Centre, Dublin City University, Dublin, 9 Ireland S. Naher, Materials Processing Research Centre, Dublin City University, Dublin, 9 Ireland Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Hybrid organic/inorganic thin-film transistors (TFTs) with bottom-contact configuration were fabricated using the Laser Induced Forward Transfer (LIFT) process. The semiconducting polymer P3HT was laser printed from a donor to a receiver substrate in order to form the active layer of the TFTs. With a single laser pulse, P3HT pixels were successfully printed. The printed material was analyzed morphologically by means of Optical Microscopy and its thickness was measured by profilometry. In addition, structural characterization of P3HT thin films before and after laser printing took place by using UV-Visible absorption spectroscopy and X-Ray Diffraction. It was found that the crystallinity of the investigated films is improved upon annealing. An organic thin-film transistor (OTFT) with laser printed P3HT pixel as a channel layer was then fabricated. The OTFTs indicated a field-effect mobility up to 2.23⋅10 −4  cm 2 /Vs and an on/off ratio on the order of 10–100. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7134-9 Authors M. Makrygianni, Physics Department, National Technical University of Athens, Iroon Polytehneiou 9, 15780 Zografou, Athens, Greece E. Verrelli, Physics Department, National Technical University of Athens, Iroon Polytehneiou 9, 15780 Zografou, Athens, Greece N. Boukos, NCSR Demokritos, Aghia Paraskevi, 15310 Greece S. Chatzandroulis, NCSR Demokritos, Aghia Paraskevi, 15310 Greece D. Tsoukalas, Physics Department, National Technical University of Athens, Iroon Polytehneiou 9, 15780 Zografou, Athens, Greece I. Zergioti, Physics Department, National Technical University of Athens, Iroon Polytehneiou 9, 15780 Zografou, Athens, Greece Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Si and Ge targets were simultaneously irradiated by individual two pulsed lasers, and two plumes from the targets were collided head-on with expectation to prepare hybrid nanoparticles. We investigate effects of He background gas pressure on plume collision dynamics. Three characteristic behaviors of plume expansion dynamics are observed at low, middle, and high background gas pressure regions. Interaction between the two atomic species during plume expansion was small and the effect of collision was hardly observed at a low background gas pressure, 130 Pa, while spatial evolution of the plume was suppressed at middle pressure, 270 Pa, due to collision of the two plumes. At high pressure, 2700 Pa, plume expansion is suppressed by background gas and the effect of a direct collision of two plumes was small. These results indicate that plume collision dynamics, which governs nanoparticle formation, and the mixture of Si and Ge species can be varied by background gas pressure. The deposit near the center of two targets was nanoparticles that were composed of Si and Ge. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7141-x Authors Ikurou Umezu, Department of physics, Konan University, Kobe, 658-8501 Japan Naomichi Sakamoto, Department of Science and Engineering, Iwaki Meisei University, Iwaki, 970-8551 Japan Hiroshi Fukuoka, Department of Mechanical Engineering, Nara National College of Technology, Nara, 639-1080 Japan Yasuhiro Yokoyama, Department of physics, Konan University, Kobe, 658-8501 Japan Koichiro Nobuzawa, Department of physics, Konan University, Kobe, 658-8501 Japan Akira Sugimura, Department of physics, Konan University, Kobe, 658-8501 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Electronic excitation–relaxation processes induced by ultra-short laser pulses are studied numerically for dielectric targets. A detailed kinetic approach is used in the calculations accounting for the absence of equilibrium in the electronic subsystem. Such processes as electron–photon–phonon, electron–phonon and electron–electron scatterings are considered in the model. In addition, both laser field ionization ranging from multi-photon to tunneling one, and electron impact (avalanche) ionization processes are included in the model. The calculation results provide electron energy distribution. Based on the time-evolution of the energy distribution function, we estimate the electron thermalization time as a function of laser parameters. The effect of the density of conduction band electrons on this time is examined. By using the average electron energy, a new criterion is proposed based on determined damage threshold in agreement with recent experiments (Sanner et al. in Appl. Phys. Lett. 96:071111, 2010 ). Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7130-0 Authors Nikita S. Shcheblanov, Laboratoire Hubert Curien, UMR CNRS 5516/Université de Lyon, Bat. F, 18 rue de Professeur Benoît Lauras, 42000 Saint-Etienne, France Tatiana E. Itina, Laboratoire Hubert Curien, UMR CNRS 5516/Université de Lyon, Bat. F, 18 rue de Professeur Benoît Lauras, 42000 Saint-Etienne, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Molecular Dynamics (MD) is employed to investigate nonthermal melting triggered by coherent phonon excitation in bismuth telluride, which has Peierls distortion in the lattice structure. Results showed that the structural distortion caused by coherent phonons appears as early as 80 fs, while it takes several picoseconds for the whole phonon-excited area to evolve into a liquid state. It was also found that the temperature in the phonon-excited area rises quickly within tens of femtoseconds, while the rest of the lattice remains at the initial temperature even after several picoseconds, which is separated from the high temperature region across a thin transition area. This phenomenon is analogous to the heat transfer across a solid–liquid interface, even though in our case there is no abrupt solid-liquid interface between the cold lattice and the quasiliquid. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7139-4 Authors Y. Wang, School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA X. Xu, School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The resolution enhancement of laser-induced forward transfer (LIFT) is investigated through the pre-patterning of Cr on the donor substrate. 85 nm dots are first patterned on a microscope slide, and an 800 nm wavelength and 130 fs pulse laser with a beam waist of ∼9 μm is used to transfer the Cr dots to an acceptor substrate. The threshold fluence is found to be ∼0.15 the threshold fluence of a similar continuous film, which is thought to be due to the fact that no force is needed to tear away Cr from the film itself, unlike in a continuous film experiment. Since the volume of the material limits the transfer feature sizes instead of the laser parameters, as in a continuous film system, minimum transferable feature diameters are significantly lower compared to the continuous film case. Also, the transferred feature diameters are not dependent on the laser parameters, so the diameters are consistent across a wide range of fluences. The force per unit area generated by the laser at threshold fluence is estimated to be ∼3 GPa, which is consistent with previous results in the literature. The simplified model that our pre-patterned Cr LIFT experiment represents would make it an ideal case for benchmarking molecular dynamics simulations of femtosecond laser ablation. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7159-0 Authors V. Sametoglu, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada V. Sauer, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Y. Y. Tsui, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The reflectivity variations of a dielectric thin film during the deposition of a disordered monolayer of metallic nanoparticles are studied. We present experimental results and provide theoretical physical insight into the behavior of the reflectivity signal and its dependence on the dielectric thin-film thickness and structural features of the monolayer of nanoparticles. A closed-form expression is used to describe the reflectivity of a disordered monolayer of particles on a flat substrate within the frame of a coherent-scattering model approach. It is shown that the model reproduces qualitatively the behavior of the reflectivity signal during the experiment. Finally we study the optical response in the limit of small particles for low surface coverage fractions of the monolayer to evidence the main parameters that dictate the evolution of the reflectivity signal during the growth of a monolayer of nanoparticles. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7167-0 Authors A. García-Valenzuela, Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Michoacán y Purísima S/N, Distrito Federal 09340, Mexico E. Haro-Poniatowski, Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Michoacán y Purísima S/N, Distrito Federal 09340, Mexico J. Toudert, Instituto de Óptica, CSIC, Serrano 121, Madrid, 28006 Spain R. Serna, Instituto de Óptica, CSIC, Serrano 121, Madrid, 28006 Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Pulsed laser ablation in liquid media (PLALM) is a prominent technique for the controlled fabrication of nanomaterials via rapid reactive quenching of ablated species at the interface between the plasma and liquid. Results on nanoparticles and nanocrystals formed by PLALM of silver (Ag) and antimony (Sb) solid targets in different liquid environments (Sodium Dodecyl Sulfate, distilled water) are presented. These experiments were done by irradiating solid targets of Ag and Sb with a nanosecond pulsed Nd:YAG laser output of wavelength 532 nm. Nanoparticles of silver and nanocrystals of antimony oxide (Sb 2 O 3 ) obtained were characterized using UV-Vis spectrometry, Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), X-ray Energy Dispersion Analysis (EDAX) and X-ray diffractometry (XRD). The morphology of nanomaterials formed is studied as a function of surfactant environment. The silver nanoparticles obtained were spherical of size in the order of 10–35 nm in solution of SDS having different concentrations. In case of the Sb target, ablation was performed in two different molarities of SDS solution and distilled water. Nanocrystals of Sb 2 O 3 in powder form having cubic and orthorhombic phases were formed in SDS solution and as fibers of nanocrystals of cubic Sb 2 O 3 in distilled water. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7157-2 Authors M. I. Mendivil, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 B. Krishnan, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 F. A. Sanchez, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 S. Martinez, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 J. A. Aguilar-Martinez, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 G. A. Castillo, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 D. I. Garcia-Gutierrez, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 S. Shaji, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico 66450 Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this paper, lead-free 100− x (Bi 0.5 Na 0.5 )TiO 3 − x [SrTiO 3 ] composites ceramics with (0≤ x ≤9) were synthesized by the solid-state reaction method. Their structure, dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction patterns, Rietveld refinement data and Raman spectra revealed that the SrTiO 3 cubic structure was completely diffused into the (Bi 0.5 Na 0.5 )TiO 3 lattice with rhombohedral structure. The scanning electron microscopy images showed change in grain morphology from rectangular-like to quasi-spherical grain with increase in SrTiO 3 content. The dielectric permittivity increases, the Curie temperature decreases and the peaks become broaden with raise of SrTiO 3 content. Ferroelectric and piezoelectric properties of these composites ceramics showed degenerated behavior with increase of SrTiO 3 . Content Type Journal Article Pages 1-9 DOI 10.1007/s00339-012-7105-1 Authors B. Parija, Department of Physics, NIT, Rourkela, Orissa, India S. K. Rout, Department of Applied Physics, BIT, Mesra, Ranchi, Jharkhand, India L. S. Cavalcante, Universidade Estadual Paulista, P.O. Box 355, CEP. 14801-907 Araraquara, SP, Brazil A. Z. Simões, Universidade Estadual Paulista, P.O. Box 355, CEP. 14801-907 Araraquara, SP, Brazil S. Panigrahi, Department of Physics, NIT, Rourkela, Orissa, India E. Longo, Universidade Estadual Paulista, P.O. Box 355, CEP. 14801-907 Araraquara, SP, Brazil N. C. Batista, Departamento de Química, UESPI, CCN, Rua João Cabral, P.O. Box 2231, 64002-150 Teresina, PI, Brazil Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Polarized Raman spectroscopy was employed to observe field-induced domain switching in BaTiO 3 -based multilayer ceramic capacitors (MLCCs). Un-polarized Raman intensities of vibration modes A1(TO2,TO3) are decreased with increasing the external field from 0 MV/m to 5 MV/m, which is caused by the decrease of c-domain volumes. This phenomenon can be visualized from the simulated image gained from the mapping results in cross polarization. It shows that the c-domains are switched to the direction of electric field (3.75 MV/m). We also found that the load to imprint Vickers indentation on the polished MLCCs surface can drive the domains out of the plane parallel to internal electrodes into in-plane textures. Meanwhile, the in-plane domains in the investigated area are switched to form a uniform orientation by the local introduced compressive stress. Due to the existence of cracks, the domains near cracks will re-orient and align with the direction of the relative tensile stress, resulting in a different orientation. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7109-x Authors Haigen Gao, State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084 People’s Republic of China Zhenxing Yue, State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084 People’s Republic of China Xiaoqing Xi, State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084 People’s Republic of China Longtu Li, State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We report a method to create gold nanoparticles of different sizes and shapes using agar–agar water solution and irradiation with light from a xenon lamp, followed by ultrashort laser pulses. No additives, such as solvents, surfactants or reducing agents, were used in the procedure. Laser irradiation (laser ablation) was important to the reduction of the nanoparticles diameter and formation of another shapes. Distilled water was used as solvent and agar–agar (hydrophilic colloid extracted from certain seaweeds) was important for the stabilization of gold nanoparticles, avoiding their agglomeration. The formation of gold nanoparticles was confirmed with ultraviolet-visible absorption and TEM microscopy. The gold nanoparticles acquired spherical, prism, and rod shapes depending on the laser parameters. Variation of laser irradiation parameters as pulse energy, irradiation time and repetition rate was assessed. The relevant mechanisms contributing for the gold nanoparticles production are discussed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7108-y Authors Ricardo Almeida de Matos, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF), Departamento de Ciências Exatas e da Terra (DCET), Universidade Federal de São Paulo (UNIFESP)—Campus Diadema, Rua Prof. Artur Riedel, 275, CEP 09972-270 Diadema, SP, Brazil Thiago da Silva Cordeiro, Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, São Paulo, Brazil Ricardo Elgul Samad, Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, São Paulo, Brazil Nilson Dias Vieira Jr, Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, São Paulo, Brazil Lilia Coronato Courrol, Universidade Federal de São Paulo—UNIFESP, São Paulo, Brazil Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This work shows the influence of conditioning the Bi target previous to the pulsed laser deposition of Bi nanocomposite films on their optical and thermo-optical properties. The nanostructured films prepared by alternate pulsed laser deposition at room temperature in vacuum consist of Bi nanostructures (NSs) with different characteristic sizes that are organized in layers and embedded in an amorphous Al 2 O 3 host. Preablation of the Bi target prior to deposition leads to higher Bi concentration and Bi NSs with larger average sizes. As a result a lower optical transmission and an enhanced thermo-optical contrast are observed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7166-1 Authors R. Serna, Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain M. Jiménez de Castro, Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain J. Toudert, Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain E. Haro-Poniatowski, Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Apartado Postal 55-534, México, 09340 DF, Mexico J. García López, Centro Nacional de Aceleradores, Universidad de Sevilla, Av. Thomas A. Edison, 41092 Sevilla, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This paper presents modification of tin sulfide (SnS) thin films by pulsed laser irradiation. Tin sulfide films of 1 μm thickness were prepared using chemical bath deposition (CBD) technique. The chemical bath contained 5 ml acetone, 12 ml of triethanolamine, 8 ml of 1 M thioacetamide, 10 ml of 4 M ammonium hydroxide and 65 ml of distilled water. The chemical bath was kept at a constant temperature of 60 °C for 6 h which resulted in SnS films with 500 nm thickness. By double deposition, the final thickness of SnS thin films obtained was 1 μm. Laser processing was conducted to modify the structure, morphology and physical properties of the SnS thin films. The laser specifications were pulsed Nd:YAG laser with 532 nm wavelength, 300 mJ pulse energy and 10 ns pulse width. Properties of the laser-irradiated SnS thin films were compared with the as-prepared SnS thin films. The changes in structure, morphology, optical and electrical properties of the laser-irradiated SnS thin films were described. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7148-3 Authors D. Avellaneda, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL, Mexico 66450 B. Krishnan, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL, Mexico 66450 T. K. Das Roy, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL, Mexico 66450 G. A. Castillo, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL, Mexico 66450 S. Shaji, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL, Mexico 66450 Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Shape-memory alloys are crucial in various industrial fields. However, a high-quality film synthesis method has not been established yet. Here we examine optimum conditions for synthesis of thin films by pulsed laser deposition of Ti–Ni alloy target in vacuum. We investigated surface morphologies and chemical compositions of the films which were obtained under various conditions. We found that the suitable Ti/Ni ratio was obtained by adjusting the distance between the target and the substrate in vacuum. In parallel, we analyzed plasma plume by optical emission spectroscopy and time-of-flight mass spectrometry. We discuss the basic behavior of ablated particles in vacuum. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7156-3 Authors Kanji Shibagaki, Department of Electrical and Electronic Engineering, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294, Japan Kota Kawano, Department of Electrical and Electronic Engineering, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294, Japan Atsuto Mori, Department of Electrical and Electronic Engineering, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Uniform InGaN nanodots were successfully grown on SiO 2 pretreated GaN surface. It was found that the InGaN nanodots were 20 nm in diameter and 5 nm in height, approximately. After the growth of two periods of InGaN/GaN quantum wells on the surface of InGaN nanodots, nanodot structure still formed in the InGaN well layer caused by the enhanced phase separation phenomenon. Dual-color emissions with different behavior were observed from photoluminescence (PL) spectrum of InGaN nanodots hybrid with InGaN/GaN quantum wells. A significant blueshift and a linewidth broadening were measured for the low-energy peak as the increase of PL excitation power, while a slight blueshift and a linewidth narrowing occurred for the high-energy peak. Accordingly, these two peaks were assigned to be from the In-rich nanodots and quantized state transition from the InGaN/GaN quantum wells with indium content, respectively. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7112-2 Authors G. F. Yang, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China P. Chen, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Z. G. Yu, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China B. Liu, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Z. L. Xie, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China X. Q. Xiu, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Z. L. Wu, Institute of Optoelectronics, Nanjing University and Yangzhou, Yangzhou, 225009 China F. Xu, Institute of Optoelectronics, Nanjing University and Yangzhou, Yangzhou, 225009 China Z. Xu, Institute of Optoelectronics, Nanjing University and Yangzhou, Yangzhou, 225009 China X. M. Hua, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China P. Han, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Y. Shi, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China R. Zhang, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Y. D. Zheng, Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials and School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The formation of laser-induced periodic surface structures (LIPSS) on titanium upon irradiation with linearly polarized femtosecond (fs) laser pulses ( τ =30 fs, λ =790 nm) in an air environment is studied experimentally and theoretically. In the experiments, the dependence on the laser fluence and the number of laser pulses per irradiation spot has been analyzed. For a moderate number of laser pulses ( N 〈1000) and at fluences between ∼0.09 and ∼0.35 J/cm 2 , predominantly low-spatial-frequency-LIPSS with periods between 400 nm and 800 nm are observed perpendicular to the polarization. In a narrow fluence range between 0.05 and 0.09 J/cm 2 , high-spatial-frequency-LIPSS with sub-100-nm spatial periods (∼ λ /10) can be generated with an orientation parallel to the polarization ( N =50). These experimental results are complemented by calculations based on a theoretical LIPSS model and compared to the present literature. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7140-y Authors J. Bonse, BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin, Germany S. Höhm, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, 12489 Berlin, Germany A. Rosenfeld, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, 12489 Berlin, Germany J. Krüger, BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We present analysis of the experiments on excitation of bismuth by ultrafast laser pulses and compare with heating bismuth in equilibrium conditions. The analysis shows that the electron–phonon relaxation time is a strong function of the lattice temperature. We developed a kinetic theory, which predicts well the experimental results. We demonstrate that lattice heating and re-structuring with the temperature-dependent energy exchange rates occurs much faster than what follows from the two-temperature model with constant relaxation factor. The analytic formulae corrected by equilibrium and non-equilibrium data allowed the interpretation of various experiments without controversy. We demonstrate that all observed ultrafast transformation of bismuth are purely thermal in nature, thus excluding the conjectures about non-thermal melting. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7126-9 Authors E. G. Gamaly, Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia A. V. Rode, Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The laser chemical processing (LCP) technique for the local doping of crystalline silicon solar cells is investigated. Here, a liquid jet containing a dopant source acts as a waveguide for pulsed laser light, which results in the melting and subsequent doping of the silicon surface. Typical LCP pulse durations are in the 15 ns range, giving satisfactory results for specific parameter settings. While great potential is assumed to exist, optimization of the pulse duration has until now not been deeply investigated, because it is hard to change this parameter in laser systems. Therefore, this paper accesses the influence of the pulse duration by a simulative approach. The model includes optics, thermodynamics, and melt dynamics induced by the liquid jet and dopant diffusion into the silicon melt. It is solved by coupling our existing finite differences Matlab-code LCPSim with the commercial fluid flow solver Ansys Fluent. Simulations of axial symmetric single pulses were performed for pulse durations ranging from 15 ns to 500 ns. Detailed results are given, which show that for longer pulse durations lateral heat conduction significantly homogenizes the inhomogeneous dopant distribution caused by the speckled intensity profile within the liquid jet cross section. The melt expulsion by the liquid jet is low enough that a sufficiently doped layer remains after full resolidification for all pulse durations. Last, temperature gradients are evaluated to give an indication on the amount of laser damage induced by thermal stress. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7144-7 Authors Andreas Fell, Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg, Germany Filip Granek, Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Photomechanical laser ablation due to focused femtosecond laser irradiation was induced on the hind legs of living mice, and its clinical influence on muscle cell proliferation was investigated via histological examination and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis to examine the expression of the gene encoding myostatin, which is a growth repressor in muscle satellite cells. The histological examination suggested that damage of the tissue due to the femtosecond laser irradiation was localized on epidermis and dermis and hardly induced in the muscle tissue below. On the other hand, gene expression of the myostatin of muscle tissue after laser irradiation was suppressed. The suppression of myostatin expression facilitates the proliferation of muscle cells, because myostatin is a growth repressor in muscle satellite cells. On the basis of these results, we recognize the potential of the femtosecond laser as a tool for noncontact, high-throughput acupuncture in the treatment of muscle disease. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7138-5 Authors Yoichiroh Hosokawa, Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara, 630-0912 Japan Mika Ohta, Division of Medical Informatics and Bioinformatics, Graduate School of Medicine, Kobe University, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017 Japan Akihiko Ito, Department of Pathology, Faculty of Medicine, Kinki University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511 Japan Yutaka Takaoka, Division of Medical Informatics and Bioinformatics, Graduate School of Medicine, Kobe University, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, 650-0017 Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Temperature dependence of dielectric properties of (1− x )Ba(Zr 0.2 Ti 0.8 )O 3 – x (Ba 0.7 Ca 0.3 )TiO 3 ( x =0.15, 0.30, and 0.50) (BZT– x BCT) thin films prepared by a sol–gel method has been investigated. The results show that there is a broad dielectric maximum near T m and the diffuse parameter γ is close to 2, indicating a nearly complete diffuse phase transition in BZT– x BCT thin films. The dielectric relaxor behaviors of the thin films well follow Vogel–Fulcher relation. The thin films show a high dielectric tunability up to 65 %, with a small variation in the temperature range from 248.15 to 373.15 K. This study indicates that the thin films, especially for x =0.50, are promising candidates for tunable device applications with good temperature stability. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7110-4 Authors Yanting Lin, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 People’s Republic of China Ni Qin, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 People’s Republic of China Guangheng Wu, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 People’s Republic of China Tongliang Sa, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 People’s Republic of China Dinghua Bao, State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this work, we report on the production of Ge nanoparticles (NPs) in an inert Ar gas atmosphere by pulsed laser deposition (PLD) at room temperature (RT). The direct deposition of energetic particles/droplets resulting from the ablation process of the target material has been avoided by using an original and customized off-axis shadow mask ( shadowed off-axis ) deposition set-up where the NPs deposition on the substrate takes place by means of scattering between the NPs formed in the vapor phase and the background Ar atoms. It is found that the Ar gas pressure parameter has a relevant role in the crystallization process, with better crystallinity obtained as the background Ar pressure is raised for the given experimental conditions. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7131-z Authors J. Martín-Sánchez, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal A. Chahboun, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal S. R. C. Pinto, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal A. G. Rolo, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal L. Marques, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal R. Serna, Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid, Spain E. M. F. Vieira, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal M. M. D. Ramos, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal M. J. M. Gomes, Centre of Physics and Physics Department, University of Minho, Braga, 4710-057 Portugal Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Two similar crossover behaviors from hardening to softening were revealed in both annealed and rolled nanocrystalline (NC) Ni by nanoindentation tests, which is totally different from that in coarse-grained samples. X-ray diffraction and transmission electron microscopy results show that the dislocation density continuously decreases with the increment of annealing temperature, whereas it first increases and then decreases with the increased rolling strain. The change of rate sensitivity in annealed NC Ni is different from that of the rolled sample. The crossover from hardening to softening by annealing is attributed to grain-boundary relaxation, while dislocation accumulation and annihilation is responsible for the crossover behavior in rolled NC Ni. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7076-2 Authors Z. H. Cao, National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing, 210093 People’s Republic of China P. Y. Li, National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing, 210093 People’s Republic of China L. Wang, National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing, 210093 People’s Republic of China Z. H. Jiang, Key Laboratory of Automobile Materials, Department of Materials Science and Engineering, Jilin University, Changchun, 130025 People’s Republic of China X. K. Meng, National Laboratory of Solid State Microstructures and Department of Material Science and Engineering, Nanjing University, Nanjing, 210093 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The study investigated the laser microhole drilling performance of polycrystalline silicon using the trepanning drilling method combined with the helix swing path with varying parameters, including laser pulse energy, pulse repetition frequency, and galvanometric scan speed. A pulsed ultraviolet laser system was used in an atmospheric condition and under deionized water. Moreover, the trepanning method was used to obtain a larger via diameter. The surface morphology, taper angle, and melted residual high were evaluated using a three-dimensional confocal laser scanning microscope and field emission scanning electron microscope. This method can produce larger holes and can be applied to crystalline silicon, multicrystalline silicon, thin-film silicon, and other materials for photovoltaic applications. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7128-7 Authors Wen-Tse Hsiao, Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076 Taiwan Shih-Feng Tseng, Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076 Taiwan Kuo-Cheng Huang, Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076 Taiwan Donyau Chiang, Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, 30076 Taiwan Ming-Fei Chen, Department of Mechatronics Engineering, National Changhua University of Education, Changhua, 50007 Taiwan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    A scarab found in grave 25 of the Monte Prama necropolis, near Cabras, Oristano, Sardinia, is of special importance for the archaeological interpretation and dating of this important archaeological site. The object has been misinterpreted in the past as composed by bone: recent archaeometric analyses showed that it is a glazed steatite of Egyptian origin and that the altered surface contains interesting phases crystallized during the high-temperature interaction of the Mg-rich talc core with the alkali-rich glass used for glazing. A novel single crystal X-ray diffraction analysis of one of the phases indicates that it is a new compound having the milarite-osumilite structure type, with a peculiar composition close to (Na 1.52 K 0.12 □ 0.36 )(Mg 3 )(Mg 1.72 Cu 0.16 Fe 0.12 )(Si 11.4 Al 0.6 )O 30 , not reported for naturally occurring minerals. The structural and crystal chemical features of the compound, together with the known high-temperature stability of the series, allow a complete interpretation of the glazing process and conditions, based on direct application of the glaze on the steatite core with subsequent treatment at temperatures above 1000 °C. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7125-x Authors G. Artioli, Dept. of Geosciences, Università di Padova, Via Gradenigo 6, Padova, Italy I. Angelini, Dept. of Geosciences, Università di Padova, Via Gradenigo 6, Padova, Italy F. Nestola, Dept. of Geosciences, Università di Padova, Via Gradenigo 6, Padova, Italy Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    FePt/Ag films were deposited on thermally oxidized Si(100) substrates by magnetron sputtering at room temperature and then the as-deposited films were annealed at 500  ∘ C. The microstructure and magnetic properties of the films have been investigated by X-ray diffraction and vibrating sample magnetometry. The results indicate that introduction of the Ag underlayer promotes an ordering transformation of the FePt phase due to thermal tensile stress between the Ag underlayer and the FePt film. The in-plane tensile stress induced by the Ag underlayer should stretch the horizontal lattice parameter of FePt; thus, it is helpful for the ordering transformation. With increasing Ag underlayer thickness, the ordering parameter and coercivity first increase and then decrease. When the Ag underlayer thickness is 12 nm, the ordering parameter and coercivity of the film reach the maximum values, respectively. The Ag underlayer thickness also affects the magnetization reversal mechanism. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7122-0 Authors Yumei Zhang, School of Materials Science and Engineering, Jilin University, Changchun, 130025 P.R. China Wenxue Yu, School of Materials Science and Engineering, Jilin University, Changchun, 130025 P.R. China Fanghui Chen, Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping, 136000 P.R. China Mei Liu, Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping, 136000 P.R. China Yongsheng Yu, School of Materials Science and Engineering, Jilin University, Changchun, 130025 P.R. China Haibo Li, Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping, 136000 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Laser-Induced Breakdown Spectroscopy (LIBS) of DNA bases Guanine and Adenine was studied using a high-power CO 2 pulsed laser ( λ =10.591 μm, τ FWHM =64 ns and fluences ranging from 25 to 70 J/cm 2 ). The strong emission of the adenine and guanine plasma, collected using a high-resolution spectrometer, at medium-vacuum conditions (4 Pa) and at 1 mm from the target, exhibits excited molecular bands of CN (B 2 Σ + –X 2 Σ + ) and excited neutral H and ionized N + and C + . The medium-weak emission is due to excited species C 2+ , C 3+ , N, O, O + , O 2+ and molecular band systems of , OH(A 2 Σ + –X 2 Π ), NH(A 3 Π –X 3 Σ − ), CH(A 2 Π –X 2 Π ), and N 2 (C 3 Π u –B 3 Π g ). We focus our attention on the temporal evolution of different atomic/ionic and molecular species. The velocity distributions for various (different) species were obtained from time-of-flight (TOF) measurements. Intensities of some lines from C + were used for determining electron temperature and their Stark-broadened profiles were employed to estimate the temporal evolution of electron density. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7163-4 Authors L. Diaz, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain L. Rubio, Departamento de Química-Física I, Facultad de Ciencias Químicas (UCM), 28040 Madrid, Spain J. J. Camacho, Departamento de Química-Física Aplicada, Facultad de Ciencias (UAM), Cantoblanco, 28049 Madrid, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this study, the electrical conduction and bipolar switching properties in transparent vanadium oxide thin films are investigated and discussed. (110)-oriented vanadium oxide thin films were well deposited onto transparent ITO substrates for the possible development of applications in the structure of system-on-panel devices. For the as-deposited vanadium oxide thin films, they were prepared for 1 h by a rf magnetron sputtering method of rf power 130 W, chamber pressure 10 mTorr, substrate temperature 550 °C, and different oxygen concentrations. In addition, the Al/V 2 O 5 /ITO device presents reliable and bipolar switching behavior. The on/off ratio and switching cycling of two stable states are found and discussed. We suggest that the current–voltage characteristics are governed by ohmic contact and Poole−Frankel emission transport model mechanisms in low- and high-voltage regions, respectively. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7116-y Authors Kai-Huang Chen, Department of Electronics Engineering and Computer Science, Tung-Fang Design University, Kaohsiung, Taiwan, ROC Chin-Hsiung Liao, Department of Physics, Military Academy, Feng-shan, Kaohsiung, 830 Taiwan, ROC Jen-Hwan Tsai, Department of Mathematics and Physics, Chinese Air Force Academy, Kangshan, Kaohsiung, Taiwan, ROC Sean Wu, Department of Electronics Engineering and Computer Science, Tung-Fang Design University, Kaohsiung, Taiwan, ROC Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We present two-dimensional measurements of the laser-induced plasma development and shock wave evolution in air. The breakdown is induced by a Q-switched Nd:YAG laser ( λ =1064 nm) with a pulse duration of 4 ns. To study these fast laser-induced phenomena, we have developed a high-speed, two frame shadowgraph method. It enables 2D visualization of a laser-induced event in two time instances, which are delayed by an arbitrary time interval in the range from 300 ps to 30 ns. The established method is based on 30 ps, green ( λ =532 nm), and linearly polarized laser pulse, which is split into two orthogonally polarized illumination pulses for direct and delayed illumination of the breakdown area. Exploiting polarization of the probe pulses, we capture two temporally and spatially separated frames with two CCD cameras. Special attention is given to the subsequent data processing, especially to the minimization of the systematic error due to alignment of both images, and to the determination of 2D velocity distribution from the captured image pairs. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7173-2 Authors Peter Gregorčič, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia Janez Diaci, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia Janez Možina, Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The optical property and the magneto-optical response were space-selectively modified in transparent Fe 3+ - and Au 3+ -doped glasses by using infrared femtosecond- (fs-) laser irradiation and subsequent annealing. This irradiation process induces the precipitation of not only magnetic spinel-type Fe-oxide nanoparticles but also Au nanoparticles inside the glasses, which shows localized surface plasmon resonance absorption at the wavelengths larger than 500 nm. As the annealing time and the temperature increases, the position of the LSPR peaks exhibits red shifts, which is due to the growth of Au nanoparticles. Faraday rotation angles as a function of wavelength were measured, and the difference spectra exhibit distinct positive peaks, indicating that the coupling between the LSPR due to the Au nanoparticles and the diamagnetism of the matrix glass is effective. To decrease the coupling with the diamagnetic glass, a two-step annealing process (at 450 °C for 90 min and at 550 °C for 30 min) was carried out after irradiation with fs-laser. The preliminary annealing at the lower temperature contributes to the precipitation of ferrimagnetic magnetite nanoparticles. Au nanoparticles were subsequently grown by annealing at 550 °C. In this case, effective coupling between the LSPR and ferrimagnetic nanoparticles has significantly suppressed the intensity of the positive peak in the Faraday spectra compared with the single annealing process. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7150-9 Authors Seisuke Nakashima, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama-shi, Kanagawa 240-8501, Japan Koji Sugioka, RIKEN—Advanced Research Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Katsumi Midorikawa, RIKEN—Advanced Research Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Kohki Mukai, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama-shi, Kanagawa 240-8501, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We report the fabrication of electrically functional polyaniline thin-film microdevices. Polyaniline films were printed in the solid phase by Laser-Induced Forward Transfer directly between Au electrodes on a Si/SiO 2 substrate. To apply solid-phase deposition, aniline was in situ polymerized on quartz substrates. Laser deposition preserves the morphology of the films and delivers sharp features with controllable dimensions. The electrical characteristics of printed polyaniline present ohmic behavior, allowing for electroactive applications. Results on gas sensing of ammonia are presented. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7127-8 Authors M. Kandyla, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece C. Pandis, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece S. Chatzandroulis, Institute of Microelectronics, NCSR Demokritos, Agia Paraksevi, Athens, 15310 Greece P. Pissis, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece I. Zergioti, Physics Department, National Technical University of Athens, 9 Iroon Polytechniou Street, Zografou, Athens, 15780 Greece Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this work we present the optimization of zinc oxide (ZnO) film properties for a thin-film transistor (TFT) application. Thin films, 50±10 nm, of ZnO were deposited by Pulsed Laser Deposition (PLD) under a variety of growth conditions. The oxygen pressure, laser fluence, substrate temperature and annealing conditions were varied as a part of this study. Mobility and carrier concentration were the focus of the optimization. While room-temperature ZnO growths followed by air and oxygen annealing showed improvement in the (002) phase formation with a carrier concentration in the order of 10 17 –10 18 /cm 3 with low mobility in the range of 0.01–0.1 cm 2 /V s, a Hall mobility of 8 cm 2 /V s and a carrier concentration of 5×10 14 /cm 3 have been achieved on a relatively low temperature growth (250 °C) of ZnO. The low carrier concentration indicates that the number of defects have been reduced by a magnitude of nearly a 1000 as compared to the room-temperature annealed growths. Also, it was very clearly seen that for the (002) oriented films of ZnO a high mobility film is achieved. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7154-5 Authors Manisha Gupta, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Fatema Rezwana Chowdhury, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Douglas Barlage, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Ying Yin Tsui, Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We prepared copper nanoparticles by ns laser ablation in pure water and in aqueous solutions of 1,10-phenanthroline at 1064 nm and 532 nm wavelengths. Although not fully impairing progressive oxidation, ligand molecules prevent the colloids to collapse. UV–vis absorption spectroscopy showed that particle production is more efficient at 1064 nm, while transmission electron microscopy gave evidence that 532-nm pulses cause photofragmentation of the structures, resulting in reduced particle size. Furthermore, from Raman and fluorescence tests we found that colloids obtained at 1064 nm show better Surface Enhanced Raman activity, while colloids obtained at 532 nm exhibit a more intense fluorescence emission. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7160-7 Authors M. Muniz-Miranda, Department of Chemistry “U. Schiff”, University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy C. Gellini, Department of Chemistry “U. Schiff”, University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy A. Simonelli, Department of Physics “E. Fermi”, University of Pisa, Largo B. Pontecorvo, 56127 Pisa, Italy M. Tiberi, Department of Physics “E. Fermi”, University of Pisa, Largo B. Pontecorvo, 56127 Pisa, Italy F. Giammanco, Department of Physics “E. Fermi”, University of Pisa, Largo B. Pontecorvo, 56127 Pisa, Italy E. Giorgetti, Institute of Complex Systems (ISC-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Using lasers to drill hard rock presents potential advantages compared to conventional mechanical drilling, such as higher penetration rates and reduced vibration. Before realistic drilling tools can be proposed, the influence of important parameters and the mechanisms involved in drilling different rocks with different lasers must be understood. In this work, we investigate the efficiency of laser drilling of granite and travertine with a CO 2 laser and a 980 nm fiber coupled diode laser. At the drilling surface, the maximum CW power delivered by the CO 2 laser was 140 W, while the diode laser delivered up to 215 W. Even at these modest power levels, it was possible to drill holes with diameters of the order of 8 mm at efficiencies varying from 40 kJ/cm 3 to 150 kJ/cm 3 . The optimum laser exposure period of time was also investigated. Finally, x-ray diffraction and fluorescence analysis, as well as Tg (Thermogravimetry) and DTA (Differential Thermal Analysis) measurements, were performed on the rocks samples used. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7143-8 Authors L. C. Guedes Valente, Dept. of Mechanical Eng., Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil M. Angélica A. Pérez, Dept. of Mechanical Eng., Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil Paula M. P. Gouvêa, Dept. of Mechanical Eng., Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil C. Martelli, Dept. of Electronics, Universidade Tecnológica Federal do Paraná, Curitiba, Brazil R. R. de Avillez, Dept. of Materials Eng., Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil Arthur M. B. Braga, Dept. of Mechanical Eng., Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We synthesized Au and ZnO nanoparticles by laser ablation in distilled water with the superposition of an ultrasonic wave. The effect of the ultrasonic wave was examined on the optical absorbance of colloidal solution and the crystallinity of synthesized nanoparticles. The absorbance of colloidal solution was enhanced by the ultrasonic wave, indicating more efficient production rate of nanoparticles. In addition, the ultrasonic wave enhanced the crystallinity of synthesized nanoparticles. These enhancements are attributed to the fact that the ultrasonic wave drives the repetitive formations and collapses of cavitation bubbles. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7161-6 Authors N. Takada, Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan A. Fujikawa, Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan N. Koshizaki, Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan K. Sasaki, Division of Quantum Science and Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The geometry structures and electronic properties of zigzag graphene nanoribbon (ZGNR) with the adsorption of transition metal atoms (Co and Ni) are investigated by using the density functional theory. The calculated results show that the interaction between Ni atom and ZGNR are stronger than that between Co atom and ZGNR. It is found that the ZGNR with Co adatom adsorbing has more possibility to show the character from semiconducting to the half-metallic one than that of the ZGNR with Ni adatom adsorbing. It is hoped that it may be valuable for investigating the GNR-based electronic devices. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7119-8 Authors Zhiyong Wang, College of Science, Guilin University of Technology, Guilin, 541008 China Jianrong Xiao, College of Science, Guilin University of Technology, Guilin, 541008 China Ming Li, College of Science, Guilin University of Technology, Guilin, 541008 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Ultrashort laser pulses are used to ablate a thin molybdenum layer from glass by irradiating the metal film through the transparent substrate. The trajectories of ablated molybdenum fragments are recorded using a shadowgraphic setup with a time resolution in the nanosecond range. In addition, the shape of collected molybdenum fragments is examined as a function of applied fluence. It is confirmed that in a fluence regime close to the ablation threshold one single disc is ablated as a whole and its velocity is determined in the order of 50 ms −1 . In a second fluence regime, partial melting at the center of the disc is found and small melt droplets are recorded on their flight. Mo fragments ablated in this regime feature a ring-like structure with a brittle fracture at the outer and a molten appearance at the inner edge. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7118-9 Authors Dominik Bartl, Robert Bosch GmbH, Postbox 300240, 70442 Stuttgart, Germany Andreas Michalowski, Robert Bosch GmbH, Postbox 300240, 70442 Stuttgart, Germany Margit Hafner, Institut für Strahlwerkzeuge, University Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart, Germany Andreas Letsch, Robert Bosch GmbH, Postbox 300240, 70442 Stuttgart, Germany Stefan Nolte, Institute of Applied Physics, Friedrich-Schiller-University, Max-Wien-Platz 1, 07743 Jena, Germany Andreas Tünnermann, Institute of Applied Physics, Friedrich-Schiller-University, Max-Wien-Platz 1, 07743 Jena, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The design and prototyping of a new double L-shaped patch antenna on substrate of available low cost polymer resin composite material is presented. The designed microstrip line fed compact antenna consists of a planar double L-shaped slotted radiating patch, 1.6 mm thick substrate and ground plane. The proposed small antenna was designed and analyzed using a finite-element method-based, commercially available, high frequency structure simulator, and fabricated on a printed circuit board. The measured −10 dB return loss bandwidths were 220 MHz and 650 MHz at 4.85 GHz and 8.10 GHz center frequencies. The corresponding symmetric and almost steady radiation patterns have peak gains of 7.6 dBi and 4.1 dBi, making the proposed antenna suitable for C and × band wireless applications, especially for WLANs, mobiles and satellites. The radiation efficiency, input impedance and current distribution of the proposed antenna were also analyzed. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7114-0 Authors M. Habib Ullah, Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia M. T. Islam, Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, Level 2, Faculty of Engineering and Built Environment Building, 43600 Bangi, Selangor, Malaysia J. S. Mandeep, Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia N. Misran, Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Ripple formation in consequence of ultrashort laser pulse irradiation of materials is a well-known phenomenon. We have investigated the formation of ripples in various metals, i.e. steel, tungsten carbide hard metal, as well as in superhard ta-C films, where we used femtosecond laser pulses of 775 nm and 387 nm mean wavelength and 150 fs pulse duration. The aim was to investigate how the ripple parameters depend on irradiation parameters, and if such ripples have a potentiality for applications. In the paper, we will show that on smooth surfaces the ripple orientation is perpendicular to the electric field vector of the linearly polarized laser beam, as is well-known. Moreover, it will be shown that the ripple period decreases with decreasing laser wavelength and/or increasing angle of incidence of the laser beam on the substrate. By using optimum parameters large areas of the materials and films can be rippled swiftly, which would be important for applications. For instance, the improvement of frictional and wear behavior of tribologically stressed surfaces by ripples was investigated on ta-C coated steel surfaces. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7146-5 Authors Manuel Pfeiffer, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Andy Engel, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Hagen Gruettner, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Katja Guenther, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Franka Marquardt, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Guenter Reisse, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Steffen Weissmantel, University of Applied Sciences Mittweida, Technikumplatz 17, 09648 Mittweida, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca 2+ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca 2+ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7137-6 Authors Chie Hosokawa, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan Yasutaka Sakamoto, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan Suguru N. Kudoh, Graduate School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan Yoichiroh Hosokawa, Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, Nara 630-0912, Japan Takahisa Taguchi, Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    KrF laser processing of polyethersulfone (PES) films at three different pulse durations regarding to the change in biocompatibility is presented with cell culture study. Various microstructure and chemistry results were obtained on the surface upon laser irradiation. It is shown that nanoscale hydrophilic ripples significantly affect the adhesion of L929 cells on the surface. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7142-9 Authors Hedieh Pazokian, Department of Physics, Laser and Optics Research School, Iran University of Science and Technology, Tehran, 1684613114 Iran Mahmoud Mollabashi, Department of Physics, Iran University of Science and Technology, Tehran, 1684613114 Iran Alexandros Selimis, Institute of Electronic Structures and Laser, Foundation for Research and Technology-Hellas, Heraklion, 71110 Crete, Greece Emmanuel Stratakis, Institute of Electronic Structures and Laser, Foundation for Research and Technology-Hellas, Heraklion, 71110 Crete, Greece Jalal Barzin, Biomaterial Department, Iran Polymer and Petrochemical Institute, Tehran, 1497713115 Iran Saeid Jelvani, Laser and Optics Research School, Tehran, 1439951113 Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this contribution we present recent experimental and theoretical results on local near-field assisted laser ablation. Along these lines, we have generated sub-diffraction sized nanostructures on fused silica substrates, exploiting the local near fields of highly ordered triangular gold nanoparticle arrays generated by nanosphere lithography. After preparation, the nanoparticle arrays were irradiated with a single 35 fs long laser pulse with a central wavelength of λ =790 nm. The pulse energy was set to E =3.9 μJ, resulting in a fluence well below the ablation threshold of the fused silica substrates. In addition, 3D electromagnetic simulations using a finite integration technique in time domain have been performed. The simulations demonstrate that indeed the local field in the vicinity of the tips of the triangular nanoparticles overcome the ablation threshold and easily explain the generated nanostructures. Most importantly, the simulations show, that higher order modes contribute to the ablation process. These modes cause ablation along the side edges of the nanoparticles. Finally, we demonstrate, that the optical properties of the triangular nanoparticles, which can be tuned by their morphology, are crucial parameters for the generation of the ablation structures. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7135-8 Authors Abdul Aleem Jamali, Computational Electronics and Photonics Group and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Wilhelmshöher Allee 71, 34121 Kassel, Germany Bernd Witzigmann, Computational Electronics and Photonics Group and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Wilhelmshöher Allee 71, 34121 Kassel, Germany Rodica Morarescu, Department of Physics and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany Thomas Baumert, Department of Physics and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany Frank Träger, Department of Physics and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany Frank Hubenthal, Department of Physics and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The development of photocathodes materials has become an important task for X-ray free electron laser and new generation of particle accelerator. The choice of the optimum cathode type and its further improvement is a fundamental issue for the progress in radio-frequency photoinjectors. Metallic photocathodes offer several advantages over the semiconductor ones, e.g. long lifetime and prompt response time on the photoemission. This paper reviews the requirements and the current status of metallic photocathodes prepared by pulsed laser ablation deposition technique. Magnesium, yttrium and lead are proposed as good alternative to copper photocathode which is generally used in radio-frequency photoinjectors. Parametric studies of the irradiation conditions are demanded to optimize the metallic thin film deposition. The main achievements on the morphology and structure characterization as well as photoemission testing of metallic photocathodes are presented and discussed. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7168-z Authors A. Lorusso, National Institute of Nuclear Physics, Mathematics and Physics Department, University of Salento, Via Arnesano, 73100 Lecce, Italy Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This paper intends to demonstrate the feasibility of a miniaturized multi-purpose metamaterial sensor that can be effectively used for chemical, biological and pressure sensing in microwave and terahertz applications. This novel sensor design makes use of the double-sided split ring resonator (DSRR) topology that is modified to have an additional sensing medium sandwiched between two identical broadside coupled SRR unit cells. The resonance frequency of the resulting DSRR sensor shifts as the dielectric permittivity or thickness of this interlayer medium changes in response to variations in an environmental parameter such as temperature, humidity, density, concentration or pressure. As a proof of concept study, both numerical and experimental results are presented with very good agreement for a multi-functional miniaturized metamaterial sensor prototype operating in X-band. Simulations for three different real-life scenarios are also presented for this sensor topology to demonstrate a moisture sensor, a density sensor and a temperature sensor with very good sensitivities where the interlayer medium is occupied by sawdust, silica aerogel and seawater, respectively. Content Type Journal Article Pages 1-9 DOI 10.1007/s00339-012-7113-1 Authors Evren Ekmekci, Department of Electronics and Communication Engineering, Suleyman Demirel University, 32260 Isparta, Turkey Gonul Turhan-Sayan, Department of Electrical and Electronics Engineering, Middle East Technical University, 06800 Ankara, Turkey Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this paper, we confirm that a structure composed only of split ring resonator (SRR) particles can produce backward waves. We present numerical and experimental results for electric near fields that give rise to the backward-wave behaviour. This phenomenon is expressed by an effective wavelength λ eff higher than λ . This structure behaves as a bianisotropic metamaterial when the SRRs reduce simultaneously to electric and magnetic dipoles. We show that the produced asymmetric current distribution in such configuration leads to a backward-wave behaviour. An extraction method based on a homogenization procedure shows a good concordance of the index of refraction between the experimental and simulation results. This method is used to quantify the magnetoelectric parameter. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7102-4 Authors Hakeim Talleb, UPMC, Université Paris 06, UR 2, L2E, 4 place Jussieu, 75005 Paris, France Zine Eddine Djeffal, UPMC, Université Paris 06, UR 2, L2E, 4 place Jussieu, 75005 Paris, France David Lautru, UPMC, Université Paris 06, UR 2, L2E, 4 place Jussieu, 75005 Paris, France Abdelwaheb Ourir, Institut Langevin, ESPCI, UMR, CNRS 7587, 10 rue Vauquelin, 75005 Paris, France Victor Fouad Hanna, UPMC, Université Paris 06, UR 2, L2E, 4 place Jussieu, 75005 Paris, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Modeling of the interaction between a dielectric material and ultrashort laser pulses provides the temporal evolution of the electronic excitation and the optical properties of the dielectric. Experimentally determined reflectances and ablation depths for sapphire are compared to the calculations. A decrease in reflectance at high fluences is observed experimentally, which demonstrates the necessity of a temperature-dependent electron scattering rate in the model. The comparison thus provides new constraints on the optical parameters of the model. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7136-7 Authors Kristian Wædegaard, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark Martin Frislev, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark Peter Balling, Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this work, we report the structure, microstructure, ferroelectric/electromechanical properties, and retention characteristics of [Bi 1− x Nb x ]FeO 3 (BNFO) thin films [ x =0,0.025,0.05, and 0.1] prepared by the polymeric precursor method. X-ray patterns analyses and Rietveld refinement data confirmed that BNFO thin films have a rhombohedral structure and can be obtained at 773 K for 2 h in static air. However, a small quantity of deleterious phase related to Bi 2 Fe 4 O 9 was observed with the addition of niobium (Nb). Structural refinement data indicated that the substitution of bismuth (Bi) by Nb in the A-site leads to a reduction in lattice parameters and the unit cell volume. Supercell models representing the [BiO 6 ],[NbO 6 ], and [FeO 6 ] clusters which are present in the rhombohedral lattice are shown here. Atomic force microscopy images showed a reduction in the average grain size of films with the substitution of Bi by Nb. Ferroelectric and electromechanical properties were confirmed by hysteresis loops and piezoresponse force microscopy. Ferroelectric/electromechanical properties and retention characteristics indicated that the BNFO films with x =0.1 have a large remnant polarization, a low coercive field, a piezoelectric coefficient ( d 33 ≈38 pm/V), and good retention resistance. Content Type Journal Article Pages 1-12 DOI 10.1007/s00339-012-7104-2 Authors A. Z. Simões, Faculdade de Engenharia de Guaratinguetá, UNESP, P.O. Box 333, 12516-410 Guaratinguetá, SP, Brazil L. S. Cavalcante, LIEC-IQ-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP, Brazil F. Moura, UNIFEI-Universidade Federal de Itajubá, Rua São Paulo, P.O. Box 377, 35900-37 Itabira, MG, Brazil N. C. Batista, CCN, Departamento de Química, UESPI, Rua João Cabral, P.O. Box 2231, 64002-150 Teresina, PI, Brazil E. Longo, LIEC-IQ-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP, Brazil J. A. Varela, LIEC-IQ-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP, Brazil Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Amorphous silicon nanowires (NWs), 3–50 nm thick and up to 4 μm long, were grown by room-temperature continuous wave laser ablation of Si in high-pressure (0.1–0.9 MPa) Ar gas without the addition of any catalysts. The diameter and length of the NWs increased as the pressures of the ambient Ar increased. Sphere-like Si particles with diameters of 4–110 nm were observed at the tips of grown NWs and their diameters exhibited a strong correlation with the NW diameters. We propose a stress-driven self-catalytic vapor-liquid-solid mechanism to explain the growth of the NWs. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7169-y Authors F. Kokai, Division of Chemistry for Material, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan S. Inoue, Division of Chemistry for Material, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan H. Hidaka, Division of Chemistry for Material, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan K. Uchiyama, Division of Chemistry for Material, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan Y. Takahashi, Division of Mechanical Engineering, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan A. Koshio, Division of Chemistry for Material, Graduate School of Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This work is aimed at an analysis of the influence on the efficiency of nanoparticle production of a cavitation bubble (CB), which forms during the laser ablation process in high-fluence regime. The CB is produced on an Au metal target immersed in water by 1064 nm ps Nd:YAG laser pulses at different fluences. Its time–space evolution is monitored by a shadowgraphic set-up, while the Au nanoparticles production rate is tagged by the growth of the plasmon resonance, which is detected by measuring shot-by-shot the UV-Vis absorbance. We analyze the dependence of bubble size on the experimental parameters. Our results appear of interest to enhance the nanoparticle production efficiency in a liquid medium. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7165-2 Authors M. Tiberi, Dept. of Physics “E. Fermi”, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy A. Simonelli, Dept. of Physics “E. Fermi”, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy G. Cristoforetti, ILIL, National Institute of Optics, Research Area of National Research Council, Via G. Moruzzi 1, 56124 Pisa, Italy P. Marsili, Institute of Complex Systems of the National Research Council ISC-CNR, Via Madonna del Piano 10, Sesto Fiorentino, FI, Italy F. Giammanco, Dept. of Physics “E. Fermi”, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy E. Giorgetti, Institute of Complex Systems of the National Research Council ISC-CNR, Via Madonna del Piano 10, Sesto Fiorentino, FI, Italy Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Composite crystals are of great interest for side-pumped thin-disc laser applications. We present a novel technique for fabricating hybrid films for such applications based upon multi-beam, multi-target Pulsed Laser Deposition (PLD). A two-garnet example was grown as proof of concept, representing the first known demonstration of controlled, continuous horizontal grading in a PLD-grown crystal. The results of shadow masking experiments and the suitability of such a method for growth of the desired structures are also discussed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7155-4 Authors Katherine A. Sloyan, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK Timothy C. May-Smith, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK Robert W. Eason, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We synthesized ZnO nanoparticles by laser ablation of a Zn target in water at pressures up to 30 MPa. We observed the enhancement of the crystallinity of synthesized ZnO nanoparticles when high pressure was applied to ambient water. In addition, we found that ZnO nanoparticles with smaller sizes were synthesized by pressurizing ambient water. Considering our previous understanding on the effect of high pressure applied to ambient liquid, the controls of the structure and the size of nanoparticles were considered to be obtained via the controls of the dynamics of laser ablation plasma and ablation-induced cavitation bubble. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7152-7 Authors W. Soliman, Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan N. Takada, Department of Electrical Engineering and Computer Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan N. Koshizaki, Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan K. Sasaki, Division of Quantum Science and Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The electronic structure and magnetic and optical properties of a 3 d transition metal M (M = V, Cr, Mn, Fe) doped (5,5) boron nitride (B 19 MN 20 ) nanotube are investigated by using the first-principles projector augmented wave potential within density functional theory under the generalized gradient approximation. It is found that B 19 VN 20 and B 19 MnN 20 systems are ideal candidates for spintronic applications, and the B 19 CrN 20 system seems to be a promising diluted magnetic semiconductor. The analyses of optical dielectric functions show that B 19 CrN 20 exhibits a new main peak at about 0.3 eV, and thus may be utilized in fields that are associated with infrared technology, such as infrared detectors, infrared masers, and so on. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7074-4 Authors Su-Fang Wang, College of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 Shaanxi, P.R. China Yan Zhang, College of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 Shaanxi, P.R. China Jian-Min Zhang, College of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 Shaanxi, P.R. China Ke-Wei Xu, State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xi’an, 710049 Shaanxi, P.R. China Vincent Ji, ICMMO/LEMHE, UMR CNRS 8182, Université Paris-Sud 11, 91405 Orsay Cedex, France Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Poly(vinylidene fluoride–trifluoroethylene), P(VDF–TrFE), electrospun membranes were obtained from a mixture of dimethylformamide (DMF) and methylethylketone (MEK) solvents. The inclusion of MEK to the solvent system promotes a faster solvent evaporation allowing complete polymer crystallization in the jet traveling between the tip and the grounded collector. The main electrospinning processing parameters were systematically changed to study their influence on fiber dimensions and distribution. Applied voltage and inner needle diameter do not have a large influence on the electrospun fiber average diameter but do on the fiber diameter distribution. On the other hand, increasing the distance between the needle tip and the collector gives origin to fibers with larger average diameter. Independently of the processing conditions, all membranes are produced in the electroactive phase of the polymer. Further, MC-3T3-E1 cell adhesion is not inhibited by the fiber membrane preparation, showing their potential use for biomedical applications. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7101-5 Authors V. Sencadas, Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal C. Ribeiro, Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal J. Nunes-Pereira, Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal V. Correia, Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal S. Lanceros-Méndez, Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The pulse train effects on femtosecond laser material processing are investigated from the viewpoint of electron dynamics on dielectrics with fused silica as a case study and metals with Al as a case study in air and water. During femtosecond laser (800 nm, 35 fs) pulse train (double pulses per train) processing of fused silica, a non-monotonic relationship between ablation size and pulse separation is observed with an abrupt rise in the range of 150–275 fs. It is assumed that this is due to the enhancement of photon–electron coupling efficiency and transition of the phase-change mechanism by adjusting the free electron density during pulse train ablation. Surface quality in Al is improved with less recast by designing the pulse energy distribution to adjust the electron/lattice temperature distribution. Furthermore, the positive effects on ablation quality by femtosecond pulse train technology are more significant in water than those in air. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7098-9 Authors Ni Leng, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 P.R. China Lan Jiang, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 P.R. China Xin Li, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 P.R. China Chuancai Xu, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 P.R. China Pengjun Liu, NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 P.R. China Yongfeng Lu, Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0511, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Amorphous silica nanowires (NWs) were simply synthesized by annealing Zn film in silicon (Si) and oxygen (O) chemical vapors produced by plasma-enhanced chemical vapor deposition (PECVD) technique with a mixture of SiH 4 and N 2 O gases. The resulting silica NWs were shown to have a silicon-rich oxide (SiO x ) phase in which the oxygen composition ( x  value) of the SiO x is controlled by varying the mixing ratio of two gases. It was found that well-defined silica (SiO 1.34 ) NWs having a mean diameter of ∼250 nm were formed by annealing Zn film (∼300 nm) at 380 °C for 10 min in Si and O vapors produced using a mixture of SiH 4 and N 2 O achieved with flow rates of 200 sccm and 60 sccm, respectively. They emit light with a peak centered at 550 nm, characteristic of SiO x materials. It is suggested that the NWs are grown via Zn/ZnO-catalyzed vapor–solid process. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7055-7 Authors Cham-Sol Choi, Department of Physics, Kangwon National University, Chuncheon, Gangwon-do 200-701, Korea Jong-Hwan Yoon, Department of Physics, Kangwon National University, Chuncheon, Gangwon-do 200-701, Korea Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This study presents an alternative method for micron-resolution patterning of a sapphire surface utilizing the characteristic of an ultra-short pulse (10 −15 s) from ytterbium (Yb) femtosecond laser (FS-laser) irradiation. Conventional processes often involve several steps, such as wet chemical or dry etching, for surface structuring of sapphire. In this study, two-dimensional array patterns on the sapphire surface with an area of 5×5 mm 2 and a depth of 1.2±0.1 μm can be directly and easily fabricated by a single step of the FS-laser process, which involves 350-fs laser pulses with a wavelength of 517 nm at a repetition rate of 100 kHz. The measured ablation depths on the sapphire surface display that the proposed process can be under well-controlled conditions. Based on the design changes for being quickly implemented in the micromachining process, a FS laser can be a promising and competitive tool for patterning sapphire with an acceptable quality for industrial usage. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7048-6 Authors Cho-Wei Chang, Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, 300 Taiwan, R.O.C. Chien-Yu Chen, Institute of Nanotechnology and Microsystems Engineering, Department of Materials Science and Engineering, National Cheng Kung University, Tainan, 701 Taiwan, R.O.C. Tien-Li Chang, Department of Mechatronic Technology, National Taiwan Normal University, 162, Sec. 1, Ho-Ping E. Road, Taipei, 106 Taiwan, R.O.C. Chia-Jen Ting, Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 Taiwan, R.O.C. Chien-Ping Wang, Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 Taiwan, R.O.C. Chang-Pin Chou, Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, 300 Taiwan, R.O.C. Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The optical reflectance, dielectric functions and phonon vibrational modes of Ti 1− x Nb x N (0≤ x ≤0.77) thin films are reported. Films of 500-nm thickness were deposited on 316LN nuclear grade stainless steel substrates by radio-frequency magnetron sputtering. The reflectance spectra of the films, in the energy range 1.5 to 5.5 eV, are fitted using the Drude–Lorentz model as the response of one Drude parameter and four Lorentz oscillators. It is demonstrated that the properties studied are dependent on Nb concentration, x , and exhibit a behavior transition threshold at x =0.5. The optical properties studied are closer to TiN for x 〈0.5 and resemble NbN for x 〉0.5. For example, the films showed a minimum in reflectance at ∼2.33 eV for values of x up to 0.5, corresponding to the Ti–N charge transfer band. Increase in Nb concentration beyond 0.5 caused a large shift in this energy to 3.2 eV, corresponding to the Nb–N charge transfer excitation. Similarly, the real part of the dielectric function is characterized by a screened plasma energy of 2.25 eV for values of x 〈0.5 (∼TiN) and 3.25±0.2 eV for x 〉0.5 (∼NbN). The energy at which the loss function reaches a peak value increases linearly for values of x from 0 to 0.41 and decreases very drastically for x 〉0.5. Phonon-vibrational modes of Ti 1− x Nb x N thin films studied by Raman spectroscopy show that Nb substitution in TiN results in first-order Raman scattering. The single-phonon acoustical peak at 270 cm −1 of TiN shifted to 265 cm −1 for x =0.77, while the two-phonon acoustical peak of TiN at 620 cm −1 shifted to 630 cm −1 for the same value of  x . The reasons for the existence of a behavior transition threshold in Nb concentration are discussed. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7012-5 Authors K. Vasu, School of Physics, University of Hyderabad, Hyderabad, 500 046 India G. M. Gopikrishnan, School of Physics, University of Hyderabad, Hyderabad, 500 046 India M. Ghanashyam Krishna, School of Physics, University of Hyderabad, Hyderabad, 500 046 India K. A. Padmanabhan, Centre for Nanotechnology, University of Hyderabad, Hyderabad, 500 046 India Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Tunnel junction based molecular devices, which utilize the two metal electrodes of a metal–insulator–metal tunnel junction as the two electrical leads to connect with molecular channels, can overcome the long standing fabrication challenges for developing futuristic molecular devices. However, producing an ultrathin insulator is the most challenging step in this tunnel junction based molecular device fabrication. A simplified molecular device approach was developed by avoiding the need of depositing a new material on the bottom electrode for growing ultrathin insulator. This paper discusses the new approach for insulator growth by one-step oxidation of a tantalum (Ta) bottom electrode, in the pholithographically defined region, i.e., ultrathin tantalum oxide (TaO x ) insulator was grown by oxidizing bottom Ta metal electrode itself. Organometallic molecular clusters (OMCs) were bridged across 1–3 nm TaO x along the perimeter of a tunnel junction to establish the highly efficient molecular conduction channels. OMC transformed the asymmetric transport profile of TaO x based tunnel junction into symmetric one. A TaO x based tunnel junction with the top ferromagnetic (NiFe) electrode exhibited the transient current suppression by several orders. Further studies by independent research groups will be needed to strengthen the current suppression phenomenon, and to realize the full potential of TaO x based molecular devices. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7022-3 Authors Pawan Tyagi, Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    A novel GMI-based microsensor with symmetrical meander structure has been fabricated by MEMS technology and mutual perpendicularity between longitudinal external field and easy axis was established by electroplating process for reaching a higher GMI. The GMI effects of the 3 and 6 turns sample with different Cu line width has been investigated systematically. The longitudinal frequency dependence has been given and a new frequency characteristic was observed in this paper. The experimental results show the increasing of Cu line width in appropriate range and more turns can respectively lead to greater GMI effect, the positive GMI ratio peak in 6 turns sample is nearly 4.5 times over the 3 turns sample, the peak frequency is greatly increased with the increasing of turn number, and the GMI ratio in 3 and 6 turns sample both exhibits negative maximum value when H L 〉50 Oe. In this work, the GMI ratio peak appears at f AC =4.8 MHz in 6 turns sample with the Cu line width of 140 μm, almost reaches 183.7 % under H L =17 Oe. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7034-z Authors Tao Wang, National Key Laboratory of Science and Technology on Nano/Micro Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Minhang Dist, Shanghai, 200240 China Chong Lei, National Key Laboratory of Science and Technology on Nano/Micro Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Minhang Dist, Shanghai, 200240 China Jian Lei, National Key Laboratory of Science and Technology on Nano/Micro Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Minhang Dist, Shanghai, 200240 China Zhen Yang, National Key Laboratory of Science and Technology on Nano/Micro Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Minhang Dist, Shanghai, 200240 China Yong Zhou, National Key Laboratory of Science and Technology on Nano/Micro Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Minhang Dist, Shanghai, 200240 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The recent observations of bright visible electroluminescence (EL) from electroformed thin film silicon based wide-gap alloys are further clamped down in a simpler structure. For this purpose, a standard quality, ordinary hydrogenated amorphous silicon (a-Si:H) homojunction pin diode was fabricated by plasma enhanced chemical vapor deposition. The fresh diode was characterized by temperature scanned current–voltage ( I – V ) and constant photocurrent measurements. The energy distribution of density of states within the forbidden gap of the intrinsic a-Si:H layer was determined by space charge limited current and optical absorption spectroscopies. Then the diode was intentionally subjected to a sufficiently high, calibrated electric field leading to its Joule heating assisted rapid crystallization at ambient atmosphere. The fresh and the formed diodes exhibit different I – V and EL characteristics. The current density of the formed diode increases drastically at low voltages while remaining unchanged at high voltages when compared to that of the fresh diode. Parallelly, the room temperature EL intensity under a particular current stress is boosted with electroforming. These interesting phenomena have been discussed in the frame of a self-consistent model. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7033-0 Authors M. Anutgan, Department of Electrical and Electronics Engineering, Karabuk University, 78050 Karabuk, Turkey T. Anutgan, Department of Physics, Karabuk University, 78050 Karabuk, Turkey I. Atilgan, Department of Materials and Metallurgical Engineering, Karabuk University, 78050 Karabuk, Turkey B. Katircioglu, Solid State Electronics Laboratory, Department of Physics, Middle East Technical University, 06531 Ankara, Turkey Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Porous Si (PS) was fabricated simply by electrochemical anodic etching of a Si wafer. By a combination of SEM, EDX and infrared spectrum measurements hydrogen-terminated crystalline Si surfaces were identified. Transparent Si nanocolloids were obtained via thermally-initiated hydrosilation of the hydrogenated Si surfaces reaction with unsaturated 1-undecene. In contrast to weak luminescence in the hydrogenated PS dispersed in toluene, intense luminescence was observed in the Si nanocolloid. In the Si nanocolloid, both strong luminescence and long-term stability can be correlated with alkylated passivation, as formation of Si–C bonds identified in infrared spectrum. Additionally, the oxidation effect was noticeable in affecting the luminescence of nano-Si during the process. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7045-9 Authors Ke Wang, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ UK Qi Wang, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ UK Yimin Chao, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Here, we introduce a selective photo-recycling scheme for organic light-emitting diode (OLED) displays. The conventional photo-recycling method, which uses a recycling film named DBEF, diminishes the ambient contrast ratio of the OLED display, so it is not suitable for display applications. The selective recycling scheme, which uses a cholesteric liquid crystal (CLC) layer that recycles light only in a specific spectral range, can minimize the deterioration of the ambient contrast ratio while improving the photo-efficiency. We found that the aperture ratio of the OLED display influences the recycling efficiency significantly, and that a thin CLC layer diminishes the ambient contrast ratio less than a thick CLC layer while it still recycles the emitted light. By recycling the blue spectral range, one can improve the lifetime of blue OLE material, which has the shortest lifetime, or reduce the size of the blue pixel, which has the largest size among red, green, and blue pixels. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7042-z Authors Eunjung Lee, School of Information & Communication Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea Jang-Kun Song, School of Information & Communication Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Ag/0.7 wt% Nb-doped SrTiO 3 (Nb:STO)/Ti structure was prepared by sputtering Ag and Ti electrodes on a Nb:STO single crystal substrate and the resistance switching (RS) properties were investigated. Reversible multilevel resistance switching behavior was obtained by applying different voltages. The resistance switching (RS) effect comes from the Schottky barrier existed between Ag and Nb:STO interface. The multilevel switching mechanism may be related to the different number of electrons trapped or detrapped by oxygen vacancies (V o 2+ ) at the Ag/Nb:STO interface, which can change the width of depletion layer. The temperature dependence on resistance of Ag/Nb:STO/Ti suggests that both high resistance state (HRS) and low resistance state (LRS) are of semiconductor behavior. Substrate annealing in vacuum degrades the RS properties of Ag/Nb:STO/Ti structure due to the increase of V o 2+ in Nb:STO. Content Type Journal Article Pages 1-4 DOI 10.1007/s00339-012-7036-x Authors Y. Zhang, Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou, 310018 China J. X. Shen, Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou, 310018 China S. L. Wang, Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou, 310018 China W. Shen, Department of Materials Science and Engineering, University of Sheffield, S1 3JD Sheffield, UK C. Cui, Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou, 310018 China P. G. Li, Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou, 310018 China B. Y. Chen, Nanometer Measurement Lab, Zhejiang Sci-Tech University, Hangzhou, 310018 China W. H. Tang, State Key Laboratory of Information Photonics & Optical Communication, Beijing University Posts and Telecommunications, Beijing, 100876 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Containerless solidification of Ni–18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7041-0 Authors D. L. Geng, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China W. J. Xie, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China B. Wei, Department of Applied Physics, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This paper reports the formation of uniform single layer micro-patterns of graphene on a glass substrate using direct femtosecond laser cutting. The cutting of graphene was achieved in air and argon. By translating the graphene sample with respect to the laser beam, continuous micro-channels were carved. The cutting geometry can be controlled by varying the laser fluence and the scanning path. Also, 1∼2 µm wide graphene micro-ribbons were hatched out. The ablation threshold of graphene was determined to be 0.16∼0.21 J/cm 2 . With the laser fluence higher than the ablation threshold, graphene was ablated rapidly and removed completely without damaging the glass substrate. Atomic force microscopy (AFM) and Raman spectroscopy have been used to confirm the ablation of graphene. Time domain finite difference modelling was employed to understand the thermal history of the laser ablation process. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7044-x Authors W. Zhang, Laser Processing Research Centre (LPRC), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL UK L. Li, Laser Processing Research Centre (LPRC), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL UK Z. B. Wang, Laser Processing Research Centre (LPRC), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL UK A. A. Pena, Laser Processing Research Centre (LPRC), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL UK D. J. Whitehead, Laser Processing Research Centre (LPRC), School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL UK M. L. Zhong, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084 China Z. Lin, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084 China H. W. Zhu, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Effects of the BiFe 0.95 Mn 0.05 O 3 thickness and a SrRuO 3 (SRO) buffer layer on the microstructure and electrical properties of BiFeO 3 /BiFe 0.95 Mn 0.05 O 3 (BFO/BFMO) bilayered thin films were investigated, where BFO/BFMO bilayered thin films were fabricated on the SRO/Pt/Ti/SiO 2 /Si(100) substrate by a radio frequency sputtering. All thin films are of a pure perovskite structure with a mixture of (110) and (111) orientations regardless of the BFMO layer thickness. Dense microstructure is demonstrated in all thin films because of the introduction of BFMO layers. The SRO buffer layer can also further improve the ferroelectric properties of BFO/BFMO bilayered thin films as compared with those of these thin films without a SRO buffer layer. The BFO/BFMO bilayered thin film with a thickness ratio of 220/120 has an enhanced ferroelectric behavior of 2 P r ∼165.23 μC/cm 2 and 2 E c ∼518.56 kV/cm, together with a good fatigue endurance. Therefore, it is an effective way to enhance the ferroelectric and fatigue properties of bismuth ferrite thin films by constructing such a bilayered structure and using a SRO buffer layer. Content Type Journal Article Category Rapid communication Pages 1-5 DOI 10.1007/s00339-012-7064-6 Authors Jiagang Wu, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Sha Qiao, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Chaohui Pu, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 P.R. China Dingquan Xiao, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China John Wang, Department of Materials Science and Engineering, National University of Singapore, Singapore, 117574 Singapore Jianguo Zhu, Department of Materials Science, Sichuan University, Chengdu, 610064 P.R. China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Light-emitting diodes (LEDs) were formed by hydrothermally growing n-ZnO nanostructures on p-GaN with or without seed layers. The performance of the fabricated LEDs was studied. The seed layers not only have a great influence on the morphology and density of the ZnO nanostructures but also determine the lighting bias and emitting mechanism. The LEDs without seed layers and with sputtered seed layers exhibit light emission only under reverse bias, which is believed due to the GaN buffer layer/p-GaN p–n junction. The LEDs with sol–gel seed layers exhibit light emission under both forward and reverse biases. With the increase of the forward bias, the LEDs first demonstrate a red electroluminescence emission coming from the sol–gel seed layers and then demonstrate an orange emission coming from the ZnO nanorods. The sol–gel seed layer and the interface play a very important role in the electroluminescence. Content Type Journal Article Pages 1-7 DOI 10.1007/s00339-012-7060-x Authors Jia-Hong Wu, State Key Laboratory of ASIC and Systems, Department of Microelectronics, Fudan University, Shanghai, 200433 China Shu-Yi Liu, State Key Laboratory of ASIC and Systems, Department of Microelectronics, Fudan University, Shanghai, 200433 China Shuti Li, Institute of Opto-Electronic Materials and Technology, South China Normal University, Guangzhou, 510631 China Yu-long Jiang, State Key Laboratory of ASIC and Systems, Department of Microelectronics, Fudan University, Shanghai, 200433 China Guo-Ping Ru, State Key Laboratory of ASIC and Systems, Department of Microelectronics, Fudan University, Shanghai, 200433 China Xin-Ping Qu, State Key Laboratory of ASIC and Systems, Department of Microelectronics, Fudan University, Shanghai, 200433 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Despite many theoretical and experimental works dealing with the impact of dense continuous liquid droplets on a flat surface, the dynamics of the impact of hollow liquid droplets is not well addressed. In an effort to understand dynamics of the hollow droplet impingement, a numerical study for the impact of a hollow droplet on a flat surface is presented. The impingement model considers the transient flow dynamics during impact and spreading of the droplet using the volume of fluid surface tracking method (VOF) coupled with the momentum transport model within a one-domain continuum formulation. The model is used to simulate the hydrodynamic behaviour of the impact of glycerin hollow droplet. It is found that the impact and spreading of the hollow droplet on a flat surface is distinctly different from the conventional dense droplet and has some new hydrodynamic features. A phenomenon of formation of a central counter jet of the liquid is predicted. With the help of simulations the cause of this phenomenon is discussed. Comparison of the predicted length of the central counter jet and the velocity of the counter jet front shows good agreements with the experimental data. The influence of the droplet initial impact velocity and the hollow droplet shell thickness on the impact behaviour is highlighted. Content Type Journal Article Pages 1-9 DOI 10.1007/s00339-012-7043-y Authors Arvind Kumar, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ UK Sai Gu, School of Engineering, Cranfield University, Cranfield, MK43 0AL UK Spyros Kamnis, School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ UK Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    In this paper we propose an original simple approach to the description of asymmetric plated heterogeneous magnetoelectric structures under external electric and magnetic fields. The existence of the considerable resonance enhancement of magnetostrictive, piezoelectric, dielectric and magnetic properties is found. The important role of the electric and magnetic interconnection influence on the effective properties is carefully analyzed. Direct and converse magnetoelectric susceptibilities are derived and compared and the difference between them is discussed. The magnetoelectric part of the results obtained for direct magnetoelectricity is compared with experiment. The comparison between plated structures and composites is done. The results are applicable far from the bending resonance frequencies, which are calculated and analyzed here. All these would be favorable for practical magnetoelectric, piezoelectric, magnetostrictive, magnetic, and dielectric resonance applications. Content Type Journal Article Pages 1-9 DOI 10.1007/s00339-012-7049-5 Authors G. S. Radchenko, Institute of Physics, South Federal University, Stachki 194, Rostov-on-Don, 344090 Russia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Silicon nanowires (SiNWs) were produced by an electroless method on FZ-Si (100) wafer, in HF/AgNO 3 solution. The influence of etching time and temperature on SiNWs morphology were studied using FESEM images. Optical properties were also investigated by optical absorption spectroscopy and low-temperature photoluminescence at 4.2 K. Considering their role as active regions, photovoltaic properties of SiNWs solar cells were studied for their different lengths. Photovoltaic measurements were taken in 1 sun condition under AM 1.5 illumination supplied by a solar simulator. Measurements indicated a reduction in efficiency as SiNWs length increased, which might be attributed to increased dangling states on nanowires surfaces. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7054-8 Authors M. Farangi, Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran M. Zahedifar, Faculty of Physics, University of Kashan, Kashan, Iran M. R. Mozdianfard, Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran M. H. Pakzamir, Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    A series of in situ transmission electron microscopy combined with scanning tunneling microscopy measurements were carried out to investigate the effect of mechanical deformation on the electrical transport properties of amorphous TiO 2 nanotubes. Under no mechanical straining, it was found that the TiO 2 nanotubes behave as electrical insulators. However, the nanotubes show semiconducting behavior under a highly deformed state. On the basis of a metal–semiconductor–metal model, it was suggested that in-shell defects, surface defect-driven conduction modes, are responsible for the appearance of the semiconducting behavior. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7040-1 Authors A. Asthana, Department of Materials Science and Engineering, Michigan Technological University, Houghton, MI 49931, USA T. Shokuhfar, Department of Mechanical Engineering–Engineering Mechanics, Michigan Technological University, Houghton, MI 49931, USA Q. Gao, Department of Mechanical Engineering–Engineering Mechanics, Michigan Technological University, Houghton, MI 49931, USA P. A. Heiden, Department of Chemistry, Michigan Technological University, Houghton, MI 49931, USA R. S. Yassar, Department of Mechanical Engineering–Engineering Mechanics, Michigan Technological University, Houghton, MI 49931, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We demonstrate a promising new material system for ionic resistive switches: nitride memristors. The switching material is an AlN film, deposited using atomic layer deposition (ALD), and the electrodes can be TiN, Pt or Al. A variety of materials characterizations were performed to determine the structure, composition and impurities of the AlN films. Content Type Journal Article Category Invited paper Pages 1-4 DOI 10.1007/s00339-012-7052-x Authors Byung Joon Choi, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA J. Joshua Yang, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA M.-X. Zhang, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA Kate J. Norris, Electrical Engineering Department, Baskin School of Engineering, University of California, Santa Cruz, CA, USA Douglas A. A. Ohlberg, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA Nobuhiko P. Kobayashi, Electrical Engineering Department, Baskin School of Engineering, University of California, Santa Cruz, CA, USA Gilberto Medeiros-Ribeiro, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA R. Stanley Williams, Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA, USA Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The analysis of the morphology of droplets printed through laser-induced forward transfer (LIFT) of liquid films shows that: (i) the droplet volume is linearly related with the energy of the laser pulse that originated it, (ii) the liquid ejection process is activated by an energy density threshold  F 0 , and (iii) the droplet volume can be correlated with a dimensional parameter of the laser beam through an oversimple model that states that the amount of printed liquid equals the liquid contained in the cylindrical portion of an irradiated film whose base corresponds to the cross-sectional area of the beam with energy density higher than  F 0 . Although these issues seem to describe correctly the LIFT process, some problematic instances arise from them. Thus, the linear relation between droplet volume and laser pulse energy seems to be inconsistent with the existence of the threshold  F 0 . On the other hand, the compatibility between the model and the aforementioned linear relation requires to be explained. Finally, the model is based on the idea that transfer takes place in a way analogous to the LIFT of solid films, but time-resolved imaging studies have demonstrated that liquid ejection follows a dynamics which seems quite unsuited with that idea. In this work previous results are re-analyzed and new experiments are performed in an attempt to clarify these questions. It is then shown that the inconsistencies pointed out are only apparent, and that the validity of the model is limited to irradiation conditions where the beam dimensions are significantly larger than the thickness of the liquid film. Furthermore, an explanation is provided for the dependence of the success and failure of the model on those irradiation conditions in terms of the diverse liquid ejection dynamics taking place. Content Type Journal Article Category Invited paper Pages 1-10 DOI 10.1007/s00339-012-7047-7 Authors M. Duocastella, Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA A. Patrascioiu, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain J. M. Fernández-Pradas, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain J. L. Morenza, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain P. Serra, Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    We report the properties of graphene oxide, a two-dimensional carbon nanomaterial, as a substrate for surface-enhanced Raman scattering. The graphene oxide substrate produced Raman enhancement for rhodamine 6G, melamine, and cephalexin. Intense characteristic D and G peaks of graphene oxide were observed when positively charged rhodamine 6G and melamine were used as the Raman probe. We attribute the appearance of D and G peaks to the aggregation of negatively charged graphene oxide. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7051-y Authors Weizi Liang, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Xiaoyun Chen, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Yu Sa, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Yuanming Feng, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Yan Wang, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Wang Lin, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072 China Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The plasmonic resonant condition, associated with scattering maximization, is analytically established for core-shell spheres with radial anisotropy in the small-radii and low-dissipation limit. A generalized expression of the effective permittivity of the scatterers is also formulated. The derived closed-form results are validated with full-wave numerical analysis. The effects of dielectric anisotropy, mode of resonance, size, and loss are further discussed. Content Type Journal Article Pages 1-8 DOI 10.1007/s00339-012-7032-1 Authors H.-Z. Liu, Department of Electrical & Computer Engineering, National University of Singapore, Singapore, 119260 Singapore K. Mouthaan, Department of Electrical & Computer Engineering, National University of Singapore, Singapore, 119260 Singapore S. Zouhdi, Laboratoire de Génie Electrique de Paris LGEP-Supélec, Plateau de Moulon, 91192 Gif-sur-Yvette, France M. S. Leong, Department of Electrical & Computer Engineering, National University of Singapore, Singapore, 119260 Singapore Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    Ultralong Cd(OH) 2 nanowires were fabricated in high yield by a convenient chemical method using alkali medium at room temperature without using any templates. The preparation conditions induce a unilateral growth of nanowires, despite the absence of any template. The length of the nanowires reached several hundreds of micrometers, giving an aspect ratio of a few thousands. The X-ray diffraction shows that the Cd(OH) 2 nanostructures crystallized in the wurtzite structure without any special orientation. The photoluminescence spectrum of Cd(OH) 2 nanostructures appears as two emission bands: one related to green emission at 475–510 nm, and the other related to deep level emission at 510–540 nm. Also the formation mechanisms of the nanowires are presented. The growth mechanism involves the irreversible and specifically oriented self-assembly of primary nanocrystals and results in the formation of the nanowires. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7056-6 Authors R. Sahraei, Department of Chemistry, University of Ilam, P.O. Box 65315-516, Ilam, Iran A. Mihandoost, Department of Physics, Faculty of Science, Arak University, Arak, 38156-8-8349 Iran G. Nabiyouni, Department of Physics, Faculty of Science, Arak University, Arak, 38156-8-8349 Iran A. Daneshfar, Department of Chemistry, University of Ilam, P.O. Box 65315-516, Ilam, Iran M. Roushani, Department of Chemistry, University of Ilam, P.O. Box 65315-516, Ilam, Iran M. H. Majles Ara, Department of Physics, Kharazmi University, P.O. Box 15614, Tehran, Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    The alternating change of electron mobility values in the modulation doped InAlAs/InGaAs/InAlAs quantum well (QW) dependently on a thickness of the InAs layer inserted in the center of the QW is theoretically predicted and experimentally observed. The electron mobility enhancement by a factor of 1.5–2 takes place when the 4 nm-thick InAs layer is inserted into the 17 nm-width QW. The experimental maximal value of the electron drift velocity at the threshold electric field for intervalley electron scattering achieves (1.8−2)×10 7  cm/s and does not nearly depend on the thickness of the InAs insert. The high value of maximal drift velocity is conserved at the additional doping of the InAs insert up to electron density of 4×10 12  cm −2 in the QW. Content Type Journal Article Pages 1-5 DOI 10.1007/s00339-012-7039-7 Authors K. Požela, Semiconductor Physics Institute, Center for Physical Sciences and Technology, Vilnius, 01108 Lithuania A. Šilėnas, Semiconductor Physics Institute, Center for Physical Sciences and Technology, Vilnius, 01108 Lithuania J. Požela, Semiconductor Physics Institute, Center for Physical Sciences and Technology, Vilnius, 01108 Lithuania V. Jucienė, Semiconductor Physics Institute, Center for Physical Sciences and Technology, Vilnius, 01108 Lithuania G. B. Galiev, Institute of Ultrahigh Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow, 117105 Russia J. S. Vasil’evskii, MEPHI National Nuclear Research University, Moscow, 115409 Russia E. A. Klimov, Institute of Ultrahigh Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow, 117105 Russia Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396

Beschreibung:    This paper indicated a simulation study to optimizing the p-i-n InGaN homojunction solar cells. From the simulation results, it was found that optimized value of cell thickness is 1.3 μm and a maximum energy conversion about 20 % can be achieved in 10 15  cm −3 defect concentration. It is shown that i -layer quality is a dominant factor in determining the performance of the cell. This result is consistent with the fact that InGaN p-i-n homojunction solar cell with higher densities of defects and dislocations exhibits a lower J sc and V oc , and consequently lower efficiency of the cell. Simulation results demonstrated that high-quality InGaN alloy is necessary to fabricate a high performance cell. Content Type Journal Article Pages 1-6 DOI 10.1007/s00339-012-7062-8 Authors Hossein Movla, Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz, Iran Davood Salami, Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz, Iran Seyed Vahid Sadreddini, Young Researchers Club, Tabriz Branch, Islamic Azad University, Tabriz, Iran Journal Applied Physics A: Materials Science & Processing Online ISSN 1432-0630 Print ISSN 0947-8396