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  • 1
    Electronic Resource
    Electronic Resource
    Material and electrical properties of highly mismatched InxGa1−xAs on GaAs by molecular-beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6912-6918 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The material properties of 2-μm-thick InxGa1−xAs epilayers grown on GaAs with 0.28≤x≤1 were investigated. It was found that for x≥0.5, the material quality of the larger lattice-mismatched heterojunction recovers, as evidenced by cross-sectional transmission electron microscopy (XTEM) and double-crystal x-ray diffraction (DXRD). Magnetophotoconductivity measurements were performed on InxGa1−xAs epilayers with 0.75≤x≤1. The dependence of both the cyclotron resonance linewidth and the carrier relaxation time on the material quality is consistent with the XTEM and DXRD results. The transport properties of InxGa1−xAs epilayers with 0.75≤x≤1 were studied using temperature-dependent van der Pauw measurements. It was found that the electron mobility in the low-temperature range is determined by a combination of ionized impurity and dislocation scatterings. The contribution of dislocation scattering to ternary InGaAs epilayers is larger than that to InAs, although InAs has a larger lattice mismatch with respect to GaAs. These four different measurement techniques confirm that the growth mode rather than lattice mismatch determines the density of dislocation for the heteroepitaxy of highly mismatched InxGa1−xAs on GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355065
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  • 2
    Electronic Resource
    Electronic Resource
    High-performance metal/SiO2/InSb capacitor fabricated by photoenhanced chemical vapor deposition (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3701-3706 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The high-performance AuCr/SiO2/InSb metal-oxide-semiconductor capacitor was fabricated successfully using photoenhanced chemical vapor deposition. The 1200-A(ring)-thick SiO2 layer was deposited on the InSb substrate at a temperature below 200 °C. Their electrical and structural properties were analyzed by capacitance-voltage and Auger electron spectroscopy, respectively. The capacitance-voltage results show that the optimal growth temperature of SiO2 is 150 °C at which the flat-band voltage of the capacitor is close to ideal and the slow interface state density is less than 5 × 1010 cm−2. For SiO2 deposited at a lower temperature, although the flat-band voltage and interface state are poorer, the subsequent thermal annealing at 150 °C for 12 h improves both quantities to the level as the optimal condition. However, for SiO2 deposited at a higher temperature (190 °C), the flat-band voltage shifts to −4 V and the slow state density increases to 1.1 × 1011 cm−2. It is found from the Auger depth profile that whatever the deposition temperature was a Si-rich region followed by an oxygen-rich region was formed at the SiO2/InSb interface. These observations are shown to be consistent with the electrical characteristics of the capacitor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346334
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  • 3
    Electronic Resource
    Electronic Resource
    Observation of X-band electron quantum interference and transport through virtual states in AlxGa1−xAs/AlAs heterostructures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4229-4232 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The X-band conduction electron quantum interference and its transport through Γ virtual state were observed in the AlxGa1−xAs/AlAs/AlxGa1−xAs/AlAs/AlxGa1−xAs heterostructures with x=0.42, 0.45, and 0.5. Due to the existence of the deep donors, the carriers in AlxGa1−xAs electrodes were frozen out at low temperature, and the current-voltage (I-V) characteristics could only be measured under illumination. For x=0.45 and 0.5, the interference patterns were clearly observed in the differential conductance (dI/dV) versus voltage plot at 8.2 K and they disappear at about 15 K for x=0.45 and 25 K for x=0.5. For x=0.42, however, the interference pattern is seen only in the d2I/dV2 vs V characteristics under low carrier concentration. The observation of this quantum interference effect leads to the conclusions that the scattering rate for X-band electrons in AlxGa1−xAs was 1.13×1012 s−1 at 25 K for x=0.5 and 8.75×1011 s−1 at 15 K for x=0.45, respectively. For x=0.42, the scattering events at 8.2 K were dominated by electron–electron and X–Γ intervalley scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354428
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  • 4
    Electronic Resource
    Electronic Resource
    The growth of highly mismatched InxGa1−xAs (0.28≤x≤1) on GaAs by molecular-beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4916-4926 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The material quality of InxGa1−xAs epilayers with 0.28≤x≤1 grown on a highly mismatched GaAs substrate and the initial growth mechanisms have been studied in detail. Cross-sectional transmission electron microscopy and double-crystal x-ray diffraction analysis of the InxGa1−xAs (x≥0.28) layers indicate that although three-dimensional island growth was found in all cases, their dislocation generation mechanisms are quite different. To study the strain relaxation process in the initial growth stage and its effects on the generation of the dislocations, 15-monolayer-thick InxGa1−xAs was grown on the GaAs. It was found that for the x=0.5 case, the thin InGaAs layer formed many small-size coherent islands; while for x=1, they changed to lower-density and much larger size relaxed islands. This shows that the growth of the highly mismatched InxGa1−xAs/GaAs heterojunction (x≥0.28) is a kinetically limited strain relaxation process. The large lattice mismatch (7.16%) between InAs and GaAs favors the early relaxation of InAs islands before they coalesce; this explains why the material quality of the InAs epilayer is better than that of InxGa1−xAs with x=0.28, 0.5, and 0.75 in spite of its larger lattice mismatch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353809
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  • 5
    Electronic Resource
    Electronic Resource
    Single and multiple AlGaAs quantum-well structures grown by liquid-phase epitaxy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2140-2145 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Al0.05Ga0.95As/Al0.35Ga0.65As single- and multiple-quantum-well structures with well widths less than 20 A(ring) have been successfully fabricated by liquid-phase epitaxy using low-temperature, two-phase, and dummy wafer methods. The transmission electron microscope cross-section technique is applied to study the thickness variation of quantum well and the transition width at the heterojunction interface. An interesting phenomenon observed during liquid-phase epitaxy growth is that the interface of Al0.05Ga0.95As grown on Al0.35Ga0.65As is rather flat and sharp whereas the opposite growth sequence gives rise to a wavy interface. It is believed that the flat Al0.05Ga0.95As/Al0.35Ga0.65As interface is due to a tendency to deposit the epilayer when the Al0.05Ga0.95As solution is in contact with the Al0.35Ga0.65As substrate and the wavy Al0.35Ga0.65As/ Al0.05Ga0.95As interface is due to a tendency to dissolve the substrate when the Al0.35Ga0.65As solution is in contact with the Al0.05Ga0.95As substrate. The transition width is less than 10 A(ring) at the Al0.05Ga0.95As/Al0.35Ga0.65As interface but is about 30–50 A(ring) at the inverted Al0.35Ga0.65As/ Al0.06Ga0.95As interface. These values are about the same as those reported in the recent literature. The peak energy of the photoluminescence spectrum reveals the quantum size effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346570
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  • 6
    Electronic Resource
    Electronic Resource
    Theoretical analysis of channel-doped amorphous silicon field-effect transistors (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1335-1339 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical characteristics of the amorphous silicon (a-Si:H) field-effect transistors have been analyzed theoretically. It is found that if no interface states exist at the SiO2 and a-Si:H interface, the transistor with undoped channel gives the best subthreshold swing and on/off current ratio. However, the existence of the interface states shifts the threshold voltage and reduces the transconductance of the transistor. It is found from numerical analysis that the problem caused by the interface states could be compensated for by doping the channel slightly with phosphorus. The physical reason for the improved performance is discussed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346703
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  • 7
    Electronic Resource
    Electronic Resource
    Stress-induced outdiffusion of Be in p+ GaAs prepared by molecular-beam epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2767-2772 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The well-known abnormal outdiffusion problem of heavily Be-doped GaAs prepared by molecular-beam epitaxy was found to be initiated by the shrinkage of the lattice constant of the (p+) GaAs epilayer. Through detailed investigation of the double-crystal x-ray spectra, van der Pauw measurements, photoluminescence, and infrared-absorption spectra of Be-doped GaAs for various doping concentrations, it is found that there exists a critical doping concentration, i.e., 2.6×1019/cm3, beyond which the lattice constant of the epilayer starts to shrink and the Be outdiffusion into the substrate is significantly enhanced. Apparently, the tensile stress on the epilayer results in the abnormal Be outdiffusion. The absorption coefficient of Be-doped GaAs in the 8–10 μm region with carrier concentration 8.3×1019/cm3 are found to be about 104 cm−1 which is useful for the application of this layer to a p+-type AlGaAs/GaAs heterojunction infrared detector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351527
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  • 8
    Electronic Resource
    Electronic Resource
    The structural and optical properties of a-SiNx:H prepared by plasma-enhanced chemical-vapor deposition (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5474-5482 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenated amorphous silicon nitride (a-SiNx:H) films have been prepared by plasma-enchanced chemical-vapor deposition with a mixture of SiH4 and NH3 at a substrate temperature of 250 and 300 °C. The properties of these films have been investigated using x-ray diffraction, infrared absorption, photoluminescence, and electron probe microanalysis. From the x-ray-diffraction measurement, it is found that the short-range order of a-SiNx:H with a basic unit of 4.31 A(ring) appears when the nitrogen-to-silicon ratio in the film exceeds 0.75 at a substrate temperature of 300 °C. In the infrared-absorption measurement, the sample was annealed repeatedly at various temperatures (300–800 °C) to identify the molecular unit responsible for each absorption peak. It is found that part of the infrared-absorption bands between 870 and 1100 cm−1 are caused not by the absorption but by the reflection of infrared radiation due to reststrahlen effect. The absorption peak at 840 cm−1 is assigned to the isolated N in the Si-host network, whereas the peak at 885 cm−1 is assigned to a local bonding arrangement involving a terminal N-H group attached to the amorphous Si network, Si-NH-Si. The transverse optical phonon of crystalline Si3N4 is found to peak at 870 cm−1. Two peaks are observed in photoluminescence experiments when the mole fraction of ammonia in gas phase is smaller than 0.8 indicating the inhomogeneity of the a-SiNx:H films. The higher-energy peak is visible in the red.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351992
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  • 9
    Electronic Resource
    Electronic Resource
    Emitter composition and geometry related surface recombination current of AlGaAs/GaAs heterojunction bipolar transistors (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5483-5488 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface recombination current at the emitter-base heterojunction of AlGaAs/GaAs heterojunction bipolar transistors prepared either by liquid phase or molecular-beam epitaxy have been studied. An ideality factor close to 1.5 was observed for those transistors with an undoped AlxGa1−xAs (x=0,0.1,0.2) spacer layer being employed in between the emitter-base heterojunction. Evidence is provided indicating that the rate-limiting process for surface current transport is the electron injection through the surface channel near the emitter-spacer junction surface. It was also found that the emitter edge-thinning design will be most effective when the emitter-base junction is graded and the exposed base surface is a wide band-gap AlGaAs layer. By using compositional grading of the emitter-base junction and emitter edge-thinning design, high gain (4200) npn AlGaAs/GaAs heterojunction bipolar transistors prepared by molecular-beam epitaxy can be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351941
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  • 10
    Electronic Resource
    Electronic Resource
    Identification of infrared absorption peaks of amorphous silicon carbon hydrogen alloy prepared using ethylene (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 125-130 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous silicon-carbon hydrogen alloy was prepared by radio frequency glow discharge decomposition of silane-ethylene mixture. The infrared absorption spectra were measured at various stages of thermal annealing. By observing the change of relative intensities between these peaks the molecular bonding responsible for the absorption peaks could be assigned. For example, in addition to the CH3 radical commonly found in films prepared by silane-methane mixture, other carbon hydrogen radicals such as CH2 and C2H5 were also unambiguously identified. At same gas phase flow ratio (Xg = 0.8), the CHx contents of ethylene-based film is about 6.6 times larger than that of the methane-based film. Hence, to grow a-SiC:H with a larger optical gap, the ethylene will be a good choice as the deposition source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350324
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