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  • 1
    Electronic Resource
    Electronic Resource
    Raman scattering study of GaN films (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4058-4062 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman spectra of GaN films grown by molecular-beam epitaxy and hydride vapor-phase epitaxy on GaAs and Al2O3 substrates have been studied. It was found that longitudinal phonon modes disappear from the spectra of n+ films due to screening by free carriers, but coupled plasmon phonon modes of the higher-energy branch are not observed because of strong damping of plasmons. Precise values for phonon frequencies and linewidths are presented. No differences in phonon frequencies for the films of different thicknesses grown on different substrates have been found which indicates that the strain due to lattice and thermal-expansion mismatch is relaxed by the formation of the dislocations very close to the substrate–film interface. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363367
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  • 2
    Electronic Resource
    Electronic Resource
    Deep level defects in GaAs on Si substrates grown by atomic hydrogen-assisted molecular beam epitaxy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4770-4772 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical activity of defects in GaAs p+n diodes grown on Si and GaAs substrates by both conventional molecular beam epitaxy (MBE) and atomic hydrogen-assisted MBE (H-MBE) were characterized by deep level transient spectroscopy. The well-known electron traps typical of MBE-grown GaAs were detected without the presence of any new levels in the upper half of the band gap. The trap densities and diode reverse saturation currents are significantly reduced in the homoepitaxial GaAs grown by H-MBE compared to that grown by MBE. The trap densities for the heteroepitaxial GaAs-on-Si grown by H-MBE have values higher than those of homoepitaxial GaAs grown by H-MBE at 330 °C, which are possibly affected by the residual dislocation density and stress. The reduction of trap density is attributed to in situ passivation of these defects by atomic H during the growth. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363415
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  • 3
    Electronic Resource
    Electronic Resource
    The X-valley transport in GaAs/AlAs triple barrier structures (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 5199-5201 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron transport through the X valley of GaAs/AlAs triple-barrier structures (TBS) grown by molecular-beam epitaxy has been studied. Negative differential resistance is observed at 77 K in one type of TBS and is identified as the result of electron transport through both the Γ and X valleys of TBS. In another type of TBS, resonant tunneling through the X valley of GaAs/AlAs TBS is observed. The Γ and X energy-band profiles under bias have been calculated in order to identify the observed features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343151
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  • 4
    Electronic Resource
    Electronic Resource
    Incorporation of nitrogen in nitride-arsenides: Origin of improved luminescence efficiency after anneal (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4401-4406 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A key to the utilization of nitride-arsenides for long wavelength optoelectronic devices is obtaining low defect materials with long nonradiative lifetimes. Currently, these materials must be annealed to obtain device quality material. The likely defect responsible for the low luminescence efficiency is associated with excess nitrogen. Photoluminescence and capacitance–voltage measurements indicate the presence of a trap associated with excess nitrogen which decreases in concentration upon anneal. Our films are grown by elemental source molecular beam epitaxy and the background impurity concentration is low, thus we have investigated the role of crystalline defects. High resolution x-ray diffraction showed improved crystal quality after anneal. We observed that the lattice parameter does not decrease linearly with nitrogen concentration for levels of nitrogen above 2.9 mol % GaN. The fact that Vegard's law is not observed, despite theoretical calculations that it should, indicates that nitrogen incorporates in locations other than the group V lattice sites. X-ray photoelectron spectroscopy revealed that nitrogen exists in two bonding configurations in not-annealed material: a Ga–N bond and another nitrogen complex in which N is less strongly bonded to gallium atoms. Annealing removes this second nitrogen complex. A combined nuclear reaction analysis and channeling technique showed that not annealed GaNAs contains a significant concentration of interstitial nitrogen that disappears upon anneal. We believe that this interstitial nitrogen is responsible for the deviation from Vegard's law and the low luminescence efficiency of not annealed GaNAs and GaInNAs quantum wells. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1352675
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  • 5
    Electronic Resource
    Electronic Resource
    X-valley tunneling in single AlAs barriers (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 988-992 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We examine tunneling through GaAs/AlAs/GaAs single-barrier heterostructures of varying widths using a tight-binding model, including in the calculation for the first time the effects of space-charge regions. Our calculation concentrates on quantities more representative of what one can measure in an experiment than previous efforts and we compare our results to both those earlier tight-binding and pseudopotential-based scattering matrix calculations, none of which include space-charge regions, and results obtained with the more usual envelope-function approach. We find that including the accumulation and depletion layers in the calculation leads to results which are somewhat unexpected in light of the older efforts. Finally, we briefly examine the role of nonzero k(parallel) (wave vector parallel to the interface) on tunneling and present current-voltage characteristics for a 10 monolayer barrier structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351777
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  • 6
    Electronic Resource
    Electronic Resource
    The design of GaAs/AlAs resonant tunneling diodes with peak current densities over 2×105 A cm−2 (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3345-3350 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A coherent transport model is described which accommodates bandstructure nonparabolicity by using a "local energy parabolic band approximation.'' The model and a knowledge of its limitations is used to design resonant tunneling diodes in the GaAs/AlAs material system with measured peak current densities of 2.5(2.8)×105 A cm−2 concurrent with peak-to-valley ratios as high as 1.8 (3.1) at room temperature (77 K).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348563
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  • 7
    Electronic Resource
    Electronic Resource
    GaAs/AlGaAs multiple-quantum-well in-line fiber intensity modulator (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 310-312 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate a GaAs/AlGaAs multiple-quantum-well in-line fiber optic intensity modulator. Based on evanescent wave coupling between a GaAs/AlGaAs multiple-quantum-well waveguide and a single-mode fiber, this device concept combines the inherent advantages of in-line fiber devices with high-speed GaAs integrated optoelectronics. The GaAs waveguide uses distributed Bragg mirror layers to phase match to the low-index fiber. Intensity modulation of the transmitted light through the fiber is achieved by tuning the effective propagation index of the GaAs waveguide via the quantum-confined Stark effect. Initial structures show a modulation contrast (ΔT/T) of more than 53%, with an applied voltage of 5 V. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124359
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  • 8
    Electronic Resource
    Electronic Resource
    Improved design of AlAs/GaAs resonant tunneling diodes (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1676-1678 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the effect of complex barrier structures in double-barrier resonant tunneling diodes (DBRTDs). The largest room-temperature peak-to-valley current ratios (PVCRs) to date have been observed for AlGaAs/GaAs DBRTDs. PVCRs as high as 5.1 were observed in AlAs/GaAs DBRTDs with an Al0.14Ga0.86As chair barrier in the cathode. We attribute the improvement in the PVCRs to the chair barrier in the cathode which significantly reduces the valley current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103114
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of Si doping in AlAs barrier layers of AlAs-GaAs-AlAs double-barrier resonant tunneling diodes (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 572-574 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlAs-GaAs-AlAs double-barrier resonant tunneling diodes (DBRTDs) with different doping levels in the AlAs layers have been investigated. Two-step spacer layers were used in all samples. Peak-to-valley current ratios (PVCRs) as high as 3.5 (11.3), 3.5 (11.3), and 2.7 (8.2) were observed at 300 K (77 K) for samples with undoped, 1.2×1017 cm−3, and 3×1018 cm−3 doped AlAs barriers, respectively. These results indicate that resonant tunneling is not strongly affected by ionized Si atoms in the AlAs barriers. The excellent PVCRs observed in DBRTDs with two-step spacer layers is not because of low background impurity densities in the active region, but because of a third barrier formed by band bending in the spacer layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101836
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  • 10
    Electronic Resource
    Electronic Resource
    Optical gain and collector current characteristics of resonant-cavity phototransistors (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1188-1190 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analytic model for current gain as a function of optical input power in heterojunction bipolar phototransistors is developed. The model provides excellent agreement with the dc measurements of a resonant-cavity-enhanced heterojunction bipolar phototransistor. The model is extended to explain small-signal results. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125978
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