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  • 1
    Electronic Resource
    Electronic Resource
    Colossal magnetoresistance behavior in LaCaMnO/CeO2/Si (100) multilayers grown by pulsed laser deposition (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5759-5759 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The La–Ca–Mn–O (LCMO) system grown on lattice matched LaAlO3 substrates by pulsed laser deposition (PLD) has attracted much recent attention because of the colossal magnetoresistance exhibited. Interest in these materials is because of their potential application in the magnetic recording industry where one of the challenges is to integrate the chip signal-conditioning circuits together with the sensing elements. We have previously reported the giant magnetoresistance characteristics of La–Ca–Mn–O films grown on Si (100) substrates by PLD. Although magnetoresistance at 50 K under a field of 4.7 T was more than 35% (Δρ/ρ0), no colossal magnetoresistance values were present, clearly due to the imperfections introduced by the lattice mismatch between film and substrate. In this paper we report the transport properties and colossal magnetoresistance behavior in LCMO/CeO2/Si(100) multilayers grown by PLD. The CeO2 is attractive as a buffer layer due to its lattice constant, a, of 5.411 Å, which is close to that of silicon (the misfit factor, being only 0.35%). And by simply rotating the unit cell 45° in the basal plane, the mismatch is less than 0.16% with LCMO along the a–b plane. It is found that the LCMO/CeO2/ Si(100) multilayers also exhibit a well-defined peak of resistivity versus temperature, a similar behavior to a single LCMO layer on a Si substrate. A magnetoresistance value of more than 93% (Δρ/ρ0) was obtained at 77 K under a field of 12 T. The films have been characterized by vibrating sample magnometer, four-point probe and scaning tunneling microscopy, and details of the influence of the multilayer preparation parameter will also be discussed. ©1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364717
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  • 2
    Electronic Resource
    Electronic Resource
    Efficient excimer ultraviolet sources from a dielectric barrier discharge in rare-gas/halogen mixtures (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 633-638 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The generation of excimer radiation in mixtures of the rare-gases Kr or Xe together with chlorine gas has been investigated by a dielectric barrier discharge. The characteristics of the emission spectra of the excimers formed, centered around 222 and 308 nm, were obtained for different gas mixtures and total gas pressures using an ultraviolet (UV) monochromator. The influence of the gas mixture, chlorine gas concentration, total gas pressure, and buffer gas dependence of the UV intensity has been investigated using chemical actinometry. Conversion efficiencies (from input electrical to output optical energy) as high as 15% can be achieved under optimal conditions. This low-cost and high-power excimer lamp system can provide an interesting alternative to conventional UV lamps for industrial large-scale UV processes. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362871
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid photochemical deposition of silicon dioxide films using an excimer lamp (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4372-4376 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have exploited the excimer light generation principle to generate large photon fluxes over a narrow band of very short wavelengths around 172 nm. By irradiating gas mixtures of silane and oxygen with this light, we have succeeded in directly photodepositing silicon dioxide films. Very high deposition rates (500 A(ring)/min) have been obtained for substrate temperatures as low as 300 °C. The deposited films have been characterized using ellipsometry and Fourier transform infrared spectroscopy. The influence of the deposition parameters on the film properties and their optimization are discussed. In particular, we describe the minimization of hydrogen incorporation in the films, rendering this new technique promising for applications in optical and electronic thin film processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357326
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  • 4
    Electronic Resource
    Electronic Resource
    Phase segregation and giant magnetoresistance behavior in as-deposited Co-Ag film grown by pulsed laser deposition : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5211-5213 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of Co-Ag granular films on Si (100) substrates by pulsed laser deposition (PLD) is reported. It is found that phase segregation can be directly produced in as-deposited Co-Ag granular films. This is attributed to the high quench rates induced by PLD, unlike the film deposited by sputtering, where post-annealing is required to achieve the required phase segregation. A large magnetoresistance (MR) value of around 27% was obtained at 4.2 K under a magnetic field of 4.7 T in as-deposited Ag0.70Co0.30 films. Our results suggest that the large magnetoresistance values obtained are strongly determined by phase segregation and particle size in association with the laser fluences used. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364470
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  • 5
    Electronic Resource
    Electronic Resource
    Structural changes produced in silicon by intense 1-μm ps pulses (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1169-1182 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The numerous bulk and surface structural changes observed in c-Si following melting with 1-μm pulses that range from 4 to 260 ps in duration and fluences from about 0.6 to 2.8 J cm−2 are examined by Nomarski and transmission electron microscope techniques. For melting pulse widths 30 ps or longer, recrystallization from the melt was observed. By contrast, for the shorter pulses (∼7 ps), the steep temperature gradients that accompany the onset of two-photon absorption associated with pulses of this width produce an undercooled melt. Under these conditions, the resolidification velocities are evidently too high to allow epitaxial regrowth from the crystalline substrate and, for the first time, regions of amorphous and large- and fine-grain polycrystalline silicon are observed to form directly on a crystalline underlayer. In addition, alternate stripes of amorphous and crystalline material are produced by these short pulses. These are associated with localized melting, demonstrating that uniform surface melting is not always required before a spatial modulation of the absorbed surface energy can occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337362
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  • 6
    Electronic Resource
    Electronic Resource
    Growth and modeling of cw-UV induced oxidation of silicon (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 227-231 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A report on the use of a low pressure Hg discharge lamp to grow 100 A(ring) SiO2 layers on Si at 550 °C. The induced reaction rate is more than 12 times that for thermal oxidation of Si at 612 °C, indicating that the growth mechanism is photonically controlled. We tentatively suggest that the induced oxidation is based on space-charge controlled drift of ionic oxygen species created in the SiO2 by charge photoinjected from the Si. Simple modeling predicts a limiting thickness for film growth that is confirmed by experimental evidence. An activation energy of 0.56 eV extracted from the data compares with values of 0.14 – 0.7 eV previously reported for oxidation of silicon by O or O− species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355888
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  • 7
    Electronic Resource
    Electronic Resource
    Vacuum ultraviolet annealing of hydroxyapatite films grown by pulsed laser deposition (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 8410-8414 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of a post-deposition vacuum ultraviolet (VUV) radiation-assisted annealing treatment performed under 1 bar of oxygen at moderate temperatures (450 °C) upon thin hydroxyapatite (HA) films grown by the pulsed laser deposition technique was investigated. The HA layers were deposited at 650 °C under different partial oxidizing pressures without any water vapor and exhibited, besides the HA crystalline phase, tetracalcium phosphate and calcium oxide phases, more so for the films grown at lower oxidizing pressures. After the VUV-assisted anneal the layers were transformed into high quality crystalline HA films, exhibiting Ca/P ratio values closer to 1.67, the value for stoichiometric HA. The content of the other crystalline phases initially present was reduced significantly. Infrared spectroscopy also showed that the amount of OH− in the films increased after the treatment. The combination of these two low temperature techniques opens the possibility of growing high quality HA layers without significant oxidation of the substrate material. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370689
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  • 8
    Electronic Resource
    Electronic Resource
    Silicon-silicon dioxide interface: An infrared study (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3195-3200 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated, using differential infrared spectroscopy, the transition region between single-crystal silicon and its natural thermally grown oxide. By monitoring the thickness-dependent behavior of the stretching mode of the Si–O bond near 1075 cm−1, we isolate bulk oxide characteristics and features arising from interface constraints, finding that films up to 100 A(ring) are still affected by interface effects. For thicker films we observe a consistent degree of asymmetry in the Si-O absorption band of about 9 cm−1, which does not exhibit a strong dependence on thickness. By contrast, the peak position, width, and degree of symmetry are found to be sensitively dependent upon film thickness below 100 A(ring), providing evidence for structurally distinct phases of silicon dioxide. Our initial interpretation suggests that the infrared spectra of such thin layers may be significantly affected by strain originating at the Si-oxide interface, rather than oxygen deficiency or overstoichiometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339320
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  • 9
    Electronic Resource
    Electronic Resource
    Deconvolution of the infrared absorption peak of the vibrational stretching mode of silicon dioxide: Evidence for structural order? (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 418-420 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is found that the characteristic infrared spectra of thermally grown silicon dioxide in the 1075 cm−1 region for films in the thickness range 28–450 A(ring) mathematically deconvolute consistently into two distinctly separate Gaussian profiles. The derived peaks are found around 1050 cm−1 with a full width at half-maximum transmission value (FWHM) of 65 cm−1, and near 1085 cm−1 with a FWHM of 35 cm−1. The relative band areas of these two features are consistently found to be approximately 0.76 and 0.24, respectively. These observations could be supportive of at least two structural models of amorphous silicon dioxide disclaiming the generally accepted continuous random network arrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98408
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  • 10
    Electronic Resource
    Electronic Resource
    Photon-controlled oxidation of silicon (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1149-1151 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A cw argon laser was used to oxidize crystalline silicon in dry oxygen. Under otherwise identical conditions, two visible wavelengths were used to identify possible nonthermal contributions to the reaction. With a simple technique to amplify small differences in the growth rate we have confirmed that the reaction is primarily thermally controlled and that there is a photonic enhancement to Si oxidation. A simulation has also provided some initial quantitative evaluation of the process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98767
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