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  • 1
    Electronic Resource
    Electronic Resource
    Exciton localization in In0.15Ga0.85As/GaAs quantum wire structures grown on (553)B-oriented GaAs substrate (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5111-5114 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using time-resolved photoluminescence (PL) measurements, we have studied the exciton localization effect in InGaAs/GaAs quantum wire (QWR) structures formed in corrugated narrow InGaAs/GaAs quantum wells (QWs) grown on (553)B GaAs substrate. The PL decay time in the QWR structure was found to be independent of the temperature for T〈70 K, showing a typical dynamical behavior of the localized excitons. This result is in striking contrast to the corresponding quantum well structures, where a linear increase of the PL decay time was observed. In addition, an increase of the exciton lifetime was observed at low temperature for the QWR structure as compared to a reference InGaAs/GaAs quantum well sample (1200 vs 400 ps). The observed longer decay time was attributed to the reduction in the spatial coherence of excitons in the QWR-like structure. In PL measurements, a significant polarization anisotropy was also found in our narrow InGaAs/GaAs QWs grown on (553)B GaAs. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1412271
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  • 2
    Electronic Resource
    Electronic Resource
    Sensitivity study of partial response maximum likelihood and peak detection channels to contamination buildup on air bearing surface of proximity recording sliders : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5402-5404 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work investigates experimentally the sensitivity of partial response maximum likelihood (PRML) and peak detection channels on the increased head-disk spacing caused by the contamination buildup on the slider's air bearing surfaces (ABS). Results obtained indicate that the peak detection channel is sensitive to both the Transition Effect (writing at increased head-disk spacing) and the Readout Resolution Effect (reading at increased head-disk spacing). The increased error rate detected in peak detection channel at increased head-disk spacing can be reduced significantly if the spacing is resumed to normal. In fact, the influence of the transition effect on the peak detection channel is more significant than the readout resolution effect. The PRML channel, however, is mostly sensitive to the transition effect only. The resolution effect, conversely, has rather limited impact on the PRML channel. Off-track sensitivity studies shows that peak shift in the peak detection channel becomes more sensitive to off-track positions when the head-disk spacing is increased. The nonlinear transition shift in the PRML channel, on the contrary, is far less sensitive to the off-track of magnetic head, even when the spacing is increased by the contamination buildup. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364553
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation characteristics and magnetic properties of iron carbide and iron ultrafine particles (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5857-5860 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic Fe3C and α-Fe ultrafine particles were prepared by laser-induced pyrolysis of Fe(CO)5 and C2H4. It is found that after passivation, the Fe3C particles exhibit a high saturation magnetization of 132 emu/g compared to that of the α-Fe particle, 95 emu/g. By determining the oxygen content and the present states of oxygen the particles contained, it is found that not only oxygen content of the α-Fe particles is much higher than that of the Fe3C particles, but the oxygen is in differnt states for the two ultrafine particles. The oxygen present on the Fe3C particles is primarily in absorbed form, compared to chemically combined oxygen as in the α-Fe particles. Thin amorphous carbon layers, formed on the surfaces of the Fe3C particles, inhibit oxidation of the Fe3C and therefore result in higher saturation magnetization achieved by Fe3C particles, relative to the α-Fe particles on which no carbon layer was present. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363570
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of iron carbonitride ultrafine particles (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7911-7915 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Iron carbonitride (ICN) ultrafine particles (20–80 nm in size) have been synthesized by laser-induced pyrolysis of Fe(CO)5–NH3–C2H4 mixture. The surface morphology, structural characteristics, oxidation behavior, and the magnetic properties of the ICN particles were reported. The role the thin carbon layer formed on the particle surface played in the oxidation behavior and in the enhancement of the magnetic properties has been studied. A carbon layer (1–2 nm) seems to protect the particles effectively from reaction of the iron carbonitride with oxygen, and the ICN particles thereby exhibit a high saturation magnetization of 142 emu/g. Additionally, the unilateral lattice expansion of the ICN compound was interpreted in terms of the structural and chemical bonding features of the ICN compound. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362403
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  • 5
    Electronic Resource
    Electronic Resource
    Alloying behavior induced by ion mixing in a system with positive heat of formation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 149-154 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous alloys were formed by room-temperature 200 keV xenon ion mixing of multilayered films in the Zr-Nb system that has a positive heat of formation (+6 kJ mol−1) and the ion-induced amorphization was found to be discontinuous in the composition range. Thermodynamic calculation was conducted and a free-energy diagram, which concerns free-energy curves of the amorphous phase and the initial state of the multilayered films with excess interfacial energy, was constructed. An interpretation to the observed discontinuity of amorphization range was presented based on the calculated free-energy diagram. In addition, two new metastable crystalline phases both of fcc structure with different lattice parameters were formed in the composition range close to pure zirconium and niobium, respectively. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360645
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  • 6
    Electronic Resource
    Electronic Resource
    Solid-state reaction to synthesize Ni-Mo metastable alloys (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3351-3356 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the Ni-Mo system, amorphous alloys and three metastable crystalline (MX) phases, i.e., an hcp (hcp-I), an enlarged hcp (hcp-II), and a fcc phase, were synthesized by solid-state reaction in the Ni-rich multilayers. An interesting point is that with increasing the annealing temperature, the hcp-I phase was formed first in the Ni67Mo33 film and then turned amorphous, while in the Ni75Mo25 film, the amorphous phase was formed first and then changed into the hcp-I phase. The compositions of three MX phases were determined experimentally. A free-energy diagram of the Ni-Mo system was established by calculating the free energies of the amorphous phase and the three MX phases, as well as those of the solid solutions and the related compounds on the basis of the model of Niessen et al. [CALPHAD 7, 51 (1981)] and Alonso's method [Solid State Commun. 46, 765 (1983)]. The calculated free-energy diagram can give relevant interpretation to the observed phase formation behaviors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357459
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature dependence of electronic conduction in thin nitrided oxides (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1832-1834 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work reports the temperature dependence of electronic conduction in thin nitrided oxides for temperatures ranging from 298 to 423 K. It was found that the conduction currents in the nitrided oxides have different temperature dependencies from those of conventional thermal oxides. At low electric fields (∼6 MV/cm), the temperature dependencies of the nitrided oxides can be divided into two segments which are attributed to the shallow trap-assisted conduction for temperature less than 400 K and Poole–Frenkel or thermionic emission for temperatures greater than 400 K, whereas the temperature dependence of thermal oxide is governed by exp(−0.143/kT) for the entire temperature range of this study. At high electric fields (∼12 MV/cm), the conduction current of nitrided oxides is mainly governed by Fowler–Nordheim tunneling for temperatures less than 340 K. In studying the temperature dependencies of the electronic trapping in nitrided oxides, we found that the density of trapped charge decreases as large as 27.8% for temperatures rising from 298 to 423 K. It indicates that the density of traps at energy levels less than 0.036 eV (measured from the conduction band of the nitrided oxide) is significantly larger than that of thermal oxides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356347
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamics and crystallographic mechanism of metastable phase formation in Nb-Fe, Nb-Co, and Nb-Ni systems by ion mixing (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4948-4952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two metastable crystalline phases, i.e., hcp and fcc, were formed in Nb-rich Nb-Fe, Nb-Co, and Nb-Ni multilayered films by room temperature 200 keV xenon ion mixing. The experimental results revealed that the formation sequence was first hcp and then fcc through an abnormal two-step phase transition of bcc→hcp→fcc. To give insight into the phase formation, Gibbs free-energy diagrams of the systems were constructed by the calculation method proposed by Alonso, Gallego, and Somozar [Nuovo Cimento, 12, 587 (1990)]. Besides, steady-state thermal annealing experiments of the corresponding as-deposited multilayers were conducted and the results confirmed the existence as well as the energetic sequence of the hcp and fcc phases predicted by the calculated free-energy diagram. Concerning the growth kinetics of the two metastable crystalline phases, the two-step phase transition was determined to be a shearing plus sliding mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355784
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  • 9
    Electronic Resource
    Electronic Resource
    Refractory metal silicides synthesized by metal vapor vacuum arc ion source implantation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3690-3696 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Refractory metal silicides, namely NbSi2, TaSi2, WSi2, and MoSi2, were successfully synthesized by using a metal vapor vacuum arc (MEVVA) ion source to implant the respective metal ions with high current density into Si(111) and Si(100) wafers. The implantation was conducted at room temperature with an extracted voltage of 40 kV. When the current densities of the refractory metal ions were up to 65 μA/cm2, the equilibrium hexagonal NbSi2 and TaSi2 phases were formed at an implantation dose of 3×1017 ions/cm2, while the hexagonal WSi2 and MoSi2 phases were formed at a dose of 5×1017 ions/cm2. With increasing the current density up to 90 μA/cm2, the transition of the hexagonal WSi2 and MoSi2 phases to their most stable tetragonal structures was observed. Postannealing at 750 and 950 °C resulted in the formation of the unique tetragonal WSi2 and MoSi2 phases, respectively. The electrical property of the MEVVA-synthesized refractory metal silicides was measured for both as-implanted and postannealed wafers. In addition, the formation of the refractory metal silicides by MEVVA implantation is discussed in terms of the beam heating effect caused by high current ion implantation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359537
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  • 10
    Electronic Resource
    Electronic Resource
    Bit-shift performance investigations at different skew angles and for different media orientations : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5649-5651 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bit-shift performance was investigated at different skew angles and for media with different orientation. Results indicate that the bit-shift value increases as the skew angle increases for both planar orientated media and near-isotropic media. As the skew angle increases, the off-track capability, described by the bit shift at different off-track distances, decreases and the bit-shift profile becomes asymmetric. Comparison of normalized bit-shift values (normalized according to the bit shift at 0° skew angle) shows that the bit shift of the near-isotropic media is not as sensitive to skew angle variation as the media with strong orientation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362270
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