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  • 1
    Electronic Resource
    Electronic Resource
    Electron beam modification of GaAs surface potential: Measurement of Richardson constant (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1890-1893 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface potential of GaAs is strongly modified in the presence of a high-energy electron beam due to the creation of electron-hole pairs in the depletion region and the subsequent drift of the holes to the surface where they neutralize surface states. This effect is modeled in terms of a parameter K=A*T2/Ib(dE/dz)η, where Ib is the beam current density, A* is the effective Richardson constant, dE/dz is the beam energy loss per unit length, and η−1 is the average energy required to create an electron-hole pair. For the sample studied here, an 0.25-μm layer with n(approximately-equal-to)3×1017 cm−3, we obtain a value K(approximately-equal-to)(7.5±0.8)×104 cm at T=296 K and Ib=0.33 μA/cm2, which gives A*(approximately-equal-to)0.44 A/cm2 K2. Although this value of A* is much lower than the theoretical estimate of 8 A/cm2 K2, it is in good agreement with other recent results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354798
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  • 2
    Electronic Resource
    Electronic Resource
    Photoquenching and thermal recovery of a thermally stimulated current peak in semi-insulating GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4971-4974 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A prominent thermally stimulated current peak T5 appearing in semi-insulating GaAs is shown to photoquench under infrared illumination, and then thermally recover at a rate r=2.0×108 exp(−0.26 eV/kT) s−1, exactly the same as that observed for EL2, within experimental error. Two possible explanations exist: (1) T5 and EL2 are microscopically very similar, probably each with an AsGa core; or (2) T5 is an electron trap that only appears to quench and recover with EL2 because EL2 controls the electron lifetime. Several other traps show similar quenching and recovery behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353816
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  • 3
    Electronic Resource
    Electronic Resource
    Defect models in electron-irradiated n-type GaAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 78-81 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 1 MeV electron irradiation has been performed in degenerate, n-type (n(approximately-equal-to)2×1017 cm−3), molecular beam epitaxial GaAs layers, and Hall effect measurements have been carried out during the irradiation in order to get accurate defect production data. The results have been fitted with statistical models, and are most consistent with the usual E1 (EC−0.045 eV) and E2 (EC−0.15 eV) levels being the (−/0) and (0/+) transitions of the As vacancy, respectively. Also, an acceptor well below EC−0.15 eV is produced at a much higher rate than that of E1 and E2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352098
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  • 4
    Electronic Resource
    Electronic Resource
    Alloy scattering in p-type AlxGa1−xAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 260-266 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The hole mobility of Be-doped ( ∼ 2 × 1017 cm−3) AlxGa1−xAs, for x=0–1, is analyzed both theoretically and experimentally. Alloy scattering is very important, and in fact reduces the hole mobility from 150 to less than 90 cm2/V s at x=0.5. The main parameter in the alloy scattering formulation, the alloy potential Eal, is found to be about 0.5 eV for p-type AlxGa1−xAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350752
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  • 5
    Electronic Resource
    Electronic Resource
    On compensation and conductivity models for molecular-beam-epitaxial GaAs grown at low temperature (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3148-3151 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Molecular-beam-epitaxial GaAs grown at 200 °C has an extremely high ((approximately-greater-than)1019 cm−3) concentration of AsGa defects and, after an anneal at 550–600 °C, a high concentration of As precipitates. The relative roles of the AsGa defects and As precipitates in compensation and conductivity is controversial. Here criteria are developed to distinguish between two existing models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349295
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of deep centers in semi-insulating liquid-encapsulated Czochralski and vertical-gradient freeze GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 8177-8182 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three-inch, semi-insulating (SI) GaAs, grown by the vertical gradient freeze (VGF) technique, has been studied by IR absorption, temperature-dependent dark current and Hall-effect, thermally stimulated current (TSC), and photoinduced current transient spectroscopy and has been compared with undoped, SI GaAs, both As-rich and Ga-rich, grown by the high-pressure liquid-encapsulated Czochralski method. The results clearly indicate that (1) the VGF GaAs contains less EL2, which suggests a less As-rich crystal stoichiometry; (2) in some VGF samples activation energies of 0.43 or 0.46 eV are deduced from temperature-dependent carrier concentration or resistivity measurements, respectively, and (3) VGF samples often show a thermal quenching behavior in the TSC peak T5. There is evidence to suggest that the 0.43 eV center is related to VAs, and T5 to VGa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347421
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  • 7
    Electronic Resource
    Electronic Resource
    Annealing dynamics of molecular-beam epitaxial GaAs grown at 200 °C (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 306-310 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By separating a 2-μm-thick molecular-beam-epitaxial GaAs layer grown at 200 °C from its 650-μm-thick substrate, we have been able to obtain accurate Hall-effect and conductivity data as functions of annealing temperature from 300 to 600 °C. At a measurement temperature of 300 K, analysis confirms that hopping conduction is much stronger than band conduction for all annealing temperatures. However, at higher measurement temperatures (up to 500 K), the band conduction becomes comparable, and a detailed analysis yields the donor and acceptor concentrations and the donor activation energy. Also, an independent absorption study yields the total and charged AsGa concentrations. Comparisons of all of these quantities as a function of annealing temperature TA show a new feature of the annealing dynamics, namely, that the dominant acceptor (probably VGa related) strongly decreases and then increases as TA is increased from 350 to 450 °C. Above 450 °C, ND, NA, and [AsGa] all decrease, as is known from previous studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354108
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  • 8
    Electronic Resource
    Electronic Resource
    Analytical two-layer Hall analysis: Application to modulation-doped field-effect transistors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 311-314 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The classical magnetic-field-dependent Hall coefficient and conductivity equations are inverted to give the mobilities μ1 and μ2 and carrier concentrations n1 (or p1) and n2 (or p2) in two degenerate bands. The two-band solution holds for arbitrary magnetic-field strength as long as quantum effects can be ignored (i.e., kT(approximately-greater-than)(h-dash-bar)eB/m*), and it is argued that the analysis can also be applied to two separate layers up to reasonable field strengths. The results are used to determine the two-dimensional electron gas mobility and carrier concentration in a modulation-doped field-effect transistor with a highly doped cap layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354109
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanisms for GaAs surface passivation by a molecular beam epitaxial cap layer grown at 200 °C (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5981-5984 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thin, undoped, molecular beam epitaxial (MBE) GaAs cap layer grown on top of an n-type conductive layer significantly reduces the free-electron depletion from the latter. By analyzing electron transfer to surface, interface, and bulk acceptor states in the cap, as a function of cap thickness, we show that either (1) the usual EC−0.7 eV surface states are absent, (2) a dense donor near EC−0.4 eV exists or (3) a high donor interface charge (∼5×1012 cm−2) is present. Any of these conclusions constitutes an important new aspect of low-temperature MBE GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350450
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  • 10
    Electronic Resource
    Electronic Resource
    Combined effects of screening and band gap renormalization on the energy of optical transitions in ZnO and GaN (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 5760-5763 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The energy positions of the optical transitions in both GaN and ZnO were investigated when the samples were excited simultaneously with a HeCd laser and an Ar+ ion laser. The increased number of free electrons excited by the Ar+ ion laser will effectively screen both the free exciton and bound exciton transitions, resulting in a blueshift. The increased number of free electrons also produces many-body effects, which lead to a reduction of the band gap energy and thus a redshift. The resultant of screening and renormalization results in a redshift of the optical transitions in ZnO but a nearly vanishing shift in GaN. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1320026
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