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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6128-6132 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon (C) doped GaAs epilayers grown by low-pressure metalorganic chemical vapor deposition have been analyzed by photoluminescence as functions of hole concentration and temperature. We have obtained an empirical relation of the effective band gap shrinkage for C doped GaAs as a function of hole concentration, ΔEg=−2.17×10−8p1/3. The temperature dependent band gap energy of C doped GaAs with a hole concentration of 9.0×1019 cm−3 has been analyzed. The resulting band gap at 0 K is (1.422±0.005) eV. The photoluminescence spectra have been analyzed on the bases of the Halperin and Lax bandtail model and an effective energy dependent optical transition matrix element. We have shown that the intensity distribution position of the photoluminescence spectrum of the conduction band to the heavy hole valence band transition is clearly separated from the intensity distribution of the conduction band to the light hole valence band transition. The conduction band to the light hole valence band transition is very prominent in the photoluminescence emission spectra of heavily C doped GaAs, and particularly at low temperatures. We have suggested that the shoulder peak which appears on the higher energy side of photoluminescence spectra is mainly due to the conduction band to the light hole valence band transition. At room temperature, the shoulder peak disappears and the full width at half maximum of the photoluminescence spectra increases; this is in good agreement with experimental results.
    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 73 (1993), S. 4703-4705 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have analyzed low temperature (12 K) photoluminescence (PL) characteristics of carbon(C) doped GaAs epilayers. No traces of donor levels were observed in the PL spectra. This suggest that well-behaved carbon is incorporated as an acceptor into the GaAs lattice. The measured peak energy of the PL intensity distribution shifts to lower energy and the full width at half maximum (FWHM) increases with increasing hole concentration. We have obtained empirical relations for FWHM of PL intensity distribution in two distinct hole concentration regions. These relations are considered to provide a useful tool to determine free hole concentration in C doped GaAs by low temperature PL measurements. As the hole concentration is increased above 2×1019 cm−3, a shoulder separated from the PL peak was observed in the PL spectra at Eg+EF, where Eg is the band gap and EF is the Fermi energy. The shoulder became very prominent at 9.2×1019 cm−3.
    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. 2747-2751 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate selenium and silicon delta-doping characteristics for GaAs layers grown by atmospheric pressure metalorganic chemical vapor deposition. Broadened capacitance-voltage (C-V) profiles and low doping activities are found in case of Se delta doping. In contrast, excellent delta-doping characteristics result for silicon. The obtained C-V full width at half maximum are in the range of 44–49 A(ring) for samples even with substrate temperatures of 700–750 °C, which are relatively high compared with the molecular-beam epitaxy (MBE) substrate temperature. Hall mobility measurements show the mobility enhancement due to a screening of impurity charges. Also, Shubnikov–de Haas oscillations demonstrate the two-dimensional nature of electrons confined in the delta-doped layers. Therefore, our delta-doped layers show no substantial differences in quality with MBE-grown delta-doped layers. In addition, preliminary delta field-effect transistors having a gate length of 1.5 μm and a gate width of 300 μm are fabricated.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3358-3361 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of short pulsed ruby laser annealing on GaAs layers grown on Si substrates by metalorganic chemical vapor deposition have been characterized by Raman spectroscopy and double-crystal x-ray diffraction. After laser melting and regrowth, the stress-released layer is formed in the near-surface. The formation of the stress-released layer results in the microcracking of the pulsed-laser-annealed GaAs surface. However, the high crystalline quality of this stress-released layer is detected. Furthermore, when GaAs layer is overgrown on this stress-released layer, this layer plays a role of blocking the dislocation threading into the overgrown GaAs layer.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1355-1358 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Capacitance-voltage (C-V) profiling of delta-doped GaAs layers grown by metalorganic chemical vapor deposition on Si substrates has been employed to demonstrate a dislocation-accelerated diffusion of Si impurities initially confined in the delta-doped sheets. A close correlation between dislocation densities in the epitaxial layers and the diffusion coefficients obtained from C-V analyses is established. After rapid thermal annealing at 800, 900, 950, and 1000 °C for 7 s, the temperature dependence of the diffusion coefficient is found to be D-30 exp(−3.4 eV/kT) for a delta-doped GaAs-on-Si with a relatively thick buffer layer of 3.3 μm. The result shows that the dislocation-accelerated diffusion of Si impurities is considerable and the inclusion of a thick buffer layer (−3 μm) is not sufficient for preventing the diffusion of the impurities into a device-active region near the GaAs surface if high temperature (〉800 °C) processing is involved.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep electron traps in GaAs layers grown on (100) 3 °-off Si substrates by metalorganic chemical vapor deposition were investigated by deep-level transient spectroscopy and a computer simulation method. The four electron traps with the activation energies of 0.81, 0.68, 0.57, and 0.53 eV below the conduction band were measured in GaAs epilayers on Si substrates, whereas only the EL2 level (Ec−0.81 eV) was detected in GaAs on a GaAs substrate. From the dependencies of concentration on the thickness of GaAs epilayer and Si substrate, it was assumed that the Ec−0.57 eV trap might be a Si-dislocation complex defect. The Ec−0.68 eV trap showed a similar behavior to that of the deep trap created in the plastically deformed bulk GaAs, and then its origin was supposed to be a defect induced by a stress due to the differences of thermal expansion coefficient and lattice parameter between Si and GaAs.
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 641-643 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray rocking curve measurements showed a significant crystallographic tilt in relaxed InGaAs layer grown on (001) GaAs. Transmission electron microscopy revealed that the origin of tilt is 60° dislocations generated having Burgers vectors of a same vertical edge component. Calculations using anisotropic elasticity show that this configuration of 60° dislocation array is energetically favorable when the tilt of epilayer is present as to remove the long range stress field induced by the vertical edge components at the interface. © 1995 American Institute of Physics.
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  • 8
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenation effects on electrical and optical properties in GaAs epilayers grown on Si substrate by metalorganic chemical vapor deposition have been investigated. In as-grown GaAs layers on Si substrates, typically four deep levels at 0.81, 0.68, 0.57, and 0.53 eV below the conduction band were observed by deep level transient spectroscopy. After hydrogen plasma exposure at 250 °C for 2.5 h, the 0.68 eV level disappeared. In addition, the reverse leakage current in the hydrogenated sample decreased by three orders of magnitude compared to the untreated sample. These effects persist after dehydrogenation process with a 5 min, 400 °C anneal. The results indicate that the hydrogenation for GaAs-on-Si has some benefits to its device application.
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Lateral growth rate of GaAs is remarkably increased with supplying CBr4, which has been utilized as a p-type dopant source for carbon doped GaAs epilayers during metalorganic chemical vapor deposition growth. The lateral growth rate can be represented as a linear function of the CBr4 flow rate, while the GaAs vertical growth rate is relatively insensitive to the CBr4 flow rate. The maximum ratio of the lateral to vertical growth rate by CBr4 is about 29. With increasing the growth temperature, the lateral growth rate increases, but it decreases at a more elevated growth temperature than 700 °C. These results are also compared to the previous results obtained by CCl4. In all cases the lateral growth rate increments by CBr4 are larger than those by CCl4. © 1996 American Institute of Physics.
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  • 10
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed the remarkable increase of GaAs lateral growth rate in the presence of CCl4 during metalorganic chemical vapor deposition (MOCVD) on patterned GaAs substrates. The lateral growth rate shows a linear dependence on CCl4 flow rate. On the other hand, the GaAs vertical growth rate is relatively insensitive to the CCl4 flow rate. The maximum ratio of lateral to vertical growth rate is about 14. Using these characteristics, we have fabricated CCl4-doped quantum wires (QWRs) on V-groove structures. The QWR structures show thickness enhancement factors, defined as the ratio of QWR thickness in the center region to the quantum well thickness in the nonpatterned region, as high as 5.6. © 1995 American Institute of Physics.
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