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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4971-4974 
    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.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 1316-1319 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaSb undoped layers grown by molecular-beam epitaxy on GaSb or on semi-insulating GaAs substrates at temperatures between 600 and 630 °C are shown to have carrier concentrations in the low 1013 cm−3 range, corresponding to almost intrinsic conditions. The materials have been characterized using current-voltage, capacitance-voltage, Hall effect, photoluminescence, thermally stimulated current, and secondary-ion mass spectrometry. Bulk GaSb (n type) is also found to have converted to high-resistance p type after a heat treatment at 630 °C. Speculations are offered for the responsible mechanism, but a definitive explanation does not exist at this time.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 1320-1322 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that when grown by molecular-beam epitaxy at high temperatures around 700 °C, undoped GaAs layers display high resistivity. Preliminary results seem to imply that Ga-related inclusions that produce internal Schottky diodes might be responsible for this effect rather than the presence of deep centers. It is proposed that Ga-related inclusions that produce internal Schottky diodes might possibly be responsible for this effect rather than the presence of deep centers.
    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 69 (1991), S. 8177-8182 
    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.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3590-3591 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple experiment involving only the measurement of dark current Idark and 1.1 μm photocurrent IPC in semi-insulating (SI) GaAs allows an accurate determination of the electron capture cross section σn for the important defect EL2 in GaAs. For 45 SI GaAs samples, from 12 different boules, grown by three different techniques, we find that IPC/Idark=1.96±0.05 at 300 K. This relationship gives σn=1.4±0.4×10−16 cm2, which is compared to previously estimated values. © 1996 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1407-1410 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For defects or impurities with deep energy levels, such as the commonly observed EL2, EL3, and EL6 in GaAs, it is very important to take account of the so-called λ effect in order to deduce the correct concentrations of these centers when using capacitance techniques. By measuring capacitance at several forward bias voltages for a given reverse bias voltage it is possible to determine concentration NT and energy ET without requiring the usual emission rate analysis. Convenient formulas for NT and ET are given, although only NT can be determined with a high degree of precision. The results for an n-type horizontal Bridgman wafer (n(approximately-equal-to)2.8×1016 cm−3) are: NEL2=(1.14±0.02)×1016 cm−3, EEL2(377 K)=0.71±0.06 eV; NEL6=(8.0±0.5)×1015 cm−3, EEL6(167 K)=0.42±0.09 eV. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1029-1032 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep-level transient spectroscopy has been performed on Si-doped GaAs layers grown by molecular-beam epitaxy at substrate temperatures of 400–450 °C. The λ effect is taken into account and overlapping peaks are analyzed numerically. An 0.65 eV electron trap of concentration 2×1016 cm−3 is believed to be related to the AsGa-associated 0.65 eV Hall-effect center, and also to the trap EB4 found in electron-irradiated GaAs.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3417-3419 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Both multistep wafer-annealed (MWA) and ingot-annealed semi-insulating (SI) GaAs wafers, grown by the Czochralski technique, are characterized by using normalized thermally stimulated current (NTSC) spectroscopy. Two main NTSC traps, T3 at 200 K and T5 at 140 K, which are thought to be related to arsenic vacancy defects, are found to be largely suppressed by MWA processes, especially by a new MWA process. Concomitant with a decrease of these traps, a significant increase of the threshold electrical field for both the thermal quenching of T5 and the low-temperature photocurrent saturation has been observed. © 1996 American Institute of Physics.
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3775-3777 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thermally stimulated current peak, occurring at 100 K for a heating rate of 0.4 K/s, has been found in semi-insulating GaN grown by molecular beam epitaxy. This peak has contributions from two traps, with the main trap described by the following parameters: emission thermal activation energy E(approximately-equal-to)90±2 meV, effective capture cross-section σ(approximately-equal-to)3±1×10−22 cm−2, and Nμτ(approximately-equal-to)3±1 × 1014 cm−1 V −1, where N is the trap concentration, μ the mobility, and τ the free-carrier lifetime. This trap is much deeper than the typical shallow donors in conducting GaN, but shallower than any of the centers reported in recent deep level transient spectroscopy measurements. © 1996 American Institute of Physics.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 260-265 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comprehensive characterization, including room temperature Hall effect, near infrared absorption, temperature dependent dark current and photocurrent (using 1.13 eV light), normalized thermally stimulated current (NTSC), photoluminescence at 4.2 K in both near band edge and deep level regions, and selective pair photoluminescence (SPL) at 2 K, has been carried out on undoped semi-insulating GaAs samples, cut from four wafers which were grown by the low pressure liquid encapsulated Czochralski technique and annealed by three different schedules: a 1100 °C anneal with either fast or slow cooling, or a 1000 °C standard anneal. The 1100 °C anneal clearly introduces higher concentrations of NTSC traps near 0.3 and 0.5 eV, a PL center at 0.8 eV, and acceptor centers, which are mainly due to the point defects and increase the resistivity. Slow cooling to some extent reduces all of these additional centers. The SPL measurements show changes in the relative intensities of C, Zn, and Si related emissions with changes in annealing conditions. © 1998 American Institute of Physics.
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