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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4546-4550 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of high-resistivity InP with resistivity up to 107 Ω cm, obtained by thermal diffusion of Cu at 800 °C for over 20 h into undoped and p-type InP samples, are investigated. Hall-effect measurements showed that the compensation mechanism in the slowly cooled sample is different from that in the quickly cooled samples. Photoluminescence was quenched in the quickly cooled samples when annealed at 350 °C and the anneal temperature at which the sample resistivity and carrier mobility reached the maximum. It is shown that the electrical compensation in the slowly cooled sample could be understood by a simple deep-level compensation model. However, the semi-insulating behavior of the quickly cooled samples appears to be consistent with an internal Schottky depletion model associated with the Cu precipitates. The photoluminescence quenching is due to the Cu precipitates acting as effective nonradiative recombination centers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6406-6412 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new boundary condition is employed in the kinematical model analysis of Bragg-peak profiles of layered single crystals, which is the dynamical reflection amplitude of the substrate instead of the previously used dynamical intensity. It is shown that this boundary condition properly accounts for the angular shift effect in the Bragg-peak profile of very thin epitaxial layers and superlattices. A kinematical model simulates properly the interference profiles in the C-layer Bragg peak of C/A/C/sub-type samples, but not in the B-layer Bragg peak of the B/A/B-type samples. The simulated and experimental rocking curves for the thin single-layer AlGaAs/GaAs and GaInAs/InP samples and for an AlGaAs/GaAs superlattice sample are discussed. Rocking curves are simulated by using the dynamical diffraction theory and the kinematical model with the old or new boundary condition. A matrix method for the dynamical theory superlattice simulation is also presented. The superlattice simulation using this matrix method is found to be substantially faster than the conventional recursive formula approach.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1303-1309 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of in-plane lattice mismatch have been studied for Ga0.92In0.08As(p+)/GaAs(n)/GaAs(n+) diodes. Different in-plane mismatch at the p–n junction was introduced by a variation of the GaInAs layer thickness (h=0.1, 0.25, 0.5, and 1 μm). Capacitance-voltage (C-V) measurements with different frequencies show a higher-frequency dispersion for a greater lattice-mismatched sample. From the frequency dependence of the C-V curve, single-level charged interface-state density (Ns) was estimated using the effective parallel capacitance and conductance components. The average charged interface density Nss was also estimated using Voltage-intercept (Vint) method. Nss shows a linear dependence on the in-plane mismatch. The charged interface state density is approximately 2.7 Δa(parallel)/a30 for partially lattice-relaxed heterojunctions. For the 1 μm sample, the forward I-V characteristic shows quasi-Fermi level pinning effect. Admittance spectroscopy measurement gives an equilibrium Fermi energy at about Ev+0.36 eV with hole capture cross section cp=2.7×10−15 cm2 for the 1 μm sample and at Ev+0.21 eV and cp=2.4×10−16 cm2 for the 0.5 μm sample.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4362-4366 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of the lattice-mismatch-induced defects on deep level traps in Ga0.92In0.08As(n+)/GaAs(p) heterojunction diodes have been studied by means of various deep level transient spectroscopy techniques and the frequency-dependent capacitance-voltage (C-V-f) characteristics. Three hole traps at 0.58, 0.42, and 0.27 eV were observed. We attribute the 0.42 eV trap to Cu impurity, the 0.58 eV trap to VGa or Fe, and the 0.27 eV trap to a complex associated with the 0.42 and 0.58 eV traps. Depth profiles of these hole traps in the GaAs side were measured in different lattice-mismatched samples. The depth profile data near the interface and from deep inside the bulk show evidence of impurity gettering by the mismatched interface. We also found that the concentrations of these traps were reduced by rapid thermal annealing. A U-shaped energy distribution of the interface states was obtained from the C-V-f measurements. For an in-plane mismatch greater than 0.25%, the interface state density shows no obvious dependence on the in-plane lattice mismatch, while at smaller mismatch the interface state density increases with increasing mismatch. The interface state density was on the order of 1011 cm−2.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1853-1859 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Self-consistent simulation results are presented for the symmetric barrier AlAs/GaAs/AlAs resonant tunneling structures with a GaInAs emitter spacer well [Appl. Phys. Lett. 58, 1077 (1991)]. A simple model is used to handle the two-dimensional emitter accumulation electrons. These accumulation electrons below the emitter launching energy are treated as pseudo three-dimensional electrons, distributed continuously down to a certain minimum energy. With a proper choice of this bottom energy, a good agreement is achieved in the peak position between the simulation results and the experimental data. The best fit value of the bottom energy for the accumulated electrons was about 2/3ΔEc below the emitter conduction band edges for all diodes. Also, the simulation results could explain the systematic variation of the experimental peak current and voltage values as a function of the GaInAs spacer well depth. In order to provide a design guideline, the layer parameters were systematically varied and the simulation results on the peak current are presented. The peak current density is found to be most sensitive to the AlAs barrier thickness, especially to the emitter barrier thickness, and it is further increased by using an emitter spacer well. Based on our theoretical analyses, a 10-A(ring) AlAs double barrier and 50-A(ring) GaAs well with a 50-A(ring) Ga0.9In0.1As emitter spacer well could produce a peak current density as high as 2200 kA/cm2.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2481-2481 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2481-2481 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1951-1954 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a simpler and more reliable method of thermoelectric effect spectroscopy (TEES), eliminating the second heater in the technique. We have applied this method to the deep level studies in the semi-insulating undoped or Cr-doped GaAs materials and in the GaAs epitaxial layers grown at a low temperature by molecular beam epitaxy. We have found that the electrical contacts made on front and back surfaces of the sample are more reliable for the TEES measurement than both contacts made on the same surface. In this contact arrangement, the temperature difference of about 1–2 K between the back and front surfaces is enough to produce a clear and reliable TEES data, without the need for a second heater. The results obtained by TEES are consistent with the results obtained by photoinduced transient spectroscopy (PITS) and by thermally stimulated current (TSC) measurements. The TEES results clearly distinguish between the electron traps and the hole traps. We discuss the results on the various semi-insulating GaAs samples and the advantages and limitations of the TEES technique.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 989-993 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep levels have been measured in a molecular beam epitaxy grown Ga0.51In0.49P/GaAs heterostructure by double correlation deep level transient spectroscopy. Gold (Au) and aluminum (Al) metals were used for a Schottky contact. A contact-related hole trap with an activation energy of 0.50–0.75 eV was observed at the Al/GaInP interface, but not at the Au/GaInP interface. To our knowledge, this contact-related trap has not been reported before. We attribute this trap to oxygen contamination, or a vacancy-related defect, VIn or VGa. A new electron trap at 0.28 eV was also observed in both Au- and Al-Schottky diodes. It depth profile showed that it is a bulk trap in a GaInP epilayer. The temperature dependent current-voltage characteristics show a large interface recombination current at the GaInP surface due to the Al contact. The energy distribution of the interface state density showed a maximum at EV+0.85 eV within the band gap. Concentration of the interface trap and the magnitude of recombination current are both reduced by a rapid thermal annealing at/or above 450 °C after aluminum deposition. The Al Schottky barrier height also increased after a 450 °C annealing.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1587-1590 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep levels in lattice-matched Ga0.51In0.49P/GaAs heterostructure have been investigated by thermal-electric effect spectroscopy (TEES) and temperature-dependent conductivity measurements. Four samples were grown by molecular-beam epitaxy with various phosphorus (P2) beam-equivalent pressures (BEP) of 0.125, 0.5, 2, and 4×10−4 Torr. A phosphorus vacancy (VP) -related deep level, an electron trap, was observed located at EC−0.28±0.02 eV. This trap dominated the conduction-band conduction at T(approximately-greater-than)220 K and was responsible for the variable-range hopping conduction when T〈220 K. Its concentration decreased with the increasing phosphorous BEP. Successive rapid thermal annealing showed that its concentration increased with the increasing annealing temperature. Another electron trap at EC−0.51 eV was also observed only in samples with P2 BEP less than 2×10−4 Torr. Its capture cross section was 4.5×10−15 cm2. This trap is attributed to VP-related complexes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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