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  • 1
    Electronic Resource
    Electronic Resource
    Strain-induced phase separation in annealed low-temperature grown Al0.3Ga0.7As (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 1790-1792 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented to show that the hydrostatic strain in a metastable Al0.3Ga0.7As film grown at low temperatures induces a one-dimensional compositional modulation upon annealing at 600 °C, a direct evidence of the existence of a miscibility gap in strained AlxGa1−xAs. A strain-driven vacancy-assisted mechanism is proposed to account for the compositional modulation and segregation of As clusters. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116668
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  • 2
    Electronic Resource
    Electronic Resource
    Al–Ga interdiffusion, carbon acceptor diffusion, and hole reduction in carbon-doped Al0.4Ga0.6As/GaAs superlattices: The As4 pressure effect (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2450-2460 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al–Ga interdiffusion, carbon acceptor diffusion, and hole reduction were studied in carbon doped Al0.4Ga0.6As/GaAs superlattices (SL) annealed under different ambient As4 pressure conditions in the temperature range of 825 °C–960 °C. The SL were doped with carbon to an initial acceptor concentration of ∼2.9×1019 cm−3. Al–Ga interdiffusion was found to be most prominent under Ga-rich annealing ambient conditions, with interdiffusivity values, DAl–Ga, turned out to be about two orders of magnitude smaller than those predicted by the Fermi-level effect model. Under As-rich ambient conditions, the DAl–Ga values are in approximate agreement with those predicted by the Fermi-level effect model. The hole concentrations in the SL decreased significantly after annealing under As-rich and As-poor ambient conditions, while those after annealing in the Ga-rich ambient were almost totally intact. By analyzing the measured hole concentration profiles, it has been found that both carbon acceptor diffusion and reduction have occurred during annealing. Both the carbon acceptor diffusivity data and the carbon acceptor reduction coefficient data are characterized approximately by a dependence on As4 pressure values to the one-quarter power. These As4 pressure dependencies indicate that carbon diffuses via the interstitialcy or interstitial–substitutional mechanism, while hole reduction is governed by a carbon acceptor precipitation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354682
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  • 3
    Electronic Resource
    Electronic Resource
    Photopumped room-temperature continuous operation of native-oxide-embedded AlyGa1−yAs-GaAs-InxGa1−xAs quantum-well-heterostructure lasers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 797-801 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on the 300 K (and 77 K) continuous photopumped laser operation of AlyGa1−yAs-GaAs-InxGa1−xAs quantum-well heterostructures (QWHs) that have been oxidized (H2O vapor+N2, 425 °C) selectively along the high-band-gap heterolayers located on either side of a GaAs waveguide (WG) region with an InxGa1−xAs QW in its center. Transmission electron microscope images show that the oxide-embedded GaAs-InxGa1−xAs WG+QW active region remains unoxidized and thus is sandwiched between electrically insulating AlyGa1−yAs native oxide layers. The thresholds for photopumped 300 K continuous laser operation of the as-grown and oxide-embedded QWHs are approximately equal after differences in the Ar+-laser photopumping efficiencies are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354868
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of heavily carbon-doped GaAs grown by metalorganic chemical vapor deposition and metalorganic molecular beam epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 981-987 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon-doped GaAs with carbon concentrations ranging from 2×1017 cm−3 to 2.6×1020 cm−3 has been characterized by variable temperature Hall effect measurements, secondary ion mass spectrometry (SIMS), and double-crystal x-ray diffraction (DCXD). The samples studied were grown by metalorganic chemical vapor deposition (MOCVD) and by metalorganic molecular beam epitaxy (MOMBE). The hole mobility is dominated by degenerate conduction for hole concentrations ≥1×1019 cm−3, and the 77 K resistivity is typically 30%–35% lower than at 300 K in these samples. The mobilities of C-doped p+-GaAs are found to be significantly higher than for Zn- or Be-doped p+-GaAs for doping concentrations in excess of 2×1018 cm−3. The maximum achievable hole mobilities for C-doped material grown by the two techniques are nearly identical, indicating that neither MOCVD nor MOMBE has an inherent advantage over the other for producing low-resistivity p-type GaAs. SIMS analysis and Hall effect measurements reveal that the total carbon concentration, [C], is higher than the as-grown hole concentration, p, in the most heavily doped samples. DCXD measurements show general agreement with the lattice mismatch predicted by Vegard's law. However, for [C](approximately-greater-than)1020 cm−3 a discrepancy between the predicted and measured mismatch suggests that partial lattice relaxation or the presence of interstitial carbon may need to be considered in order to adequately describe the lattice contraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351776
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  • 5
    Electronic Resource
    Electronic Resource
    Planar native-oxide buried-mesa AlxGa1−xAs-In0.5(AlyGa1−y)0.5P- In0.5(AlzGa1−z)0.5P visible-spectrum laser diodes (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2521-2525 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented demonstrating the continuous (cw) room-temperature (23 °C) operation of planar index-guided "buried-mesa'' AlxGa1−xAs-In0.5(AlyGa1−y)0.5P- In0.5Ga0.5P heterostructure visible-spectrum laser diodes. The planar "mesa'' structure is formed by "wet'' oxidation (H2O vapor+N2 carrier gas, 550 °C) of the AlxGa1−xAs on the composite AlxGa1−xAs-In0.5(AlyGa1−y)0.5P upper confining layer (outside of the active stripes). The oxidation process results in a ∼0.5-μm-thick native oxide located (in depth) within ∼3000 A(ring) of the active layer in the region outside of the laser stripes themselves. The oxide possesses excellent current-confinement properties and a low refractive index (n≈1.60), resulting in relatively low-threshold laser operation for narrow-stripe devices. In addition, these devices exhibit transverse-mode confinement and small beam astigmatism because of the refractive index step provided by the deep native oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351067
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  • 6
    Electronic Resource
    Electronic Resource
    InGaAs-GaAs-AlGaAs strained-layer laser with heavy silicon doping (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 568-573 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence characteristics of uniformly silicon- and beryllium-doped pseudomorphic InGaAs-GaAs-AlGaAs single- and multiple-quantum-well heterostructures grown by molecular-beam epitaxy are studied. Red shifts in the photoluminescence peaks are obtained from uniformly silicon-doped single-quantum-well samples with respect to undoped samples. Uniformly beryllium-doped InGaAs-GaAs multiple quantum wells totally intermix during materials growth. Also, the effect on laser performance (laser thresholds and emission spectra) by silicon doping is demonstrated with an InGaAs-GaAs-AlGaAs strained-layer laser (grown by molecular-beam epitaxy) with a heavily silicon-doped quantum well. The low laser threshold, kink in light versus current, shift in emission wavelength, and two emission peaks are observed, and these characteristics are believed to be due to heavy silicon doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349657
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  • 7
    Electronic Resource
    Electronic Resource
    Environmental degradation of AlxGa1−xAs-GaAs quantum-well heterostructures (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2235-2238 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data describing the deterioration of AlxGa1−xAs-GaAs heterostructures in long-term exposure (2–12 years) to normal room environmental conditions (∼20–25 °C, varying humidity) are presented. Optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron dispersion x-ray spectroscopy are used to examine AlxGa1−xAs-GaAs quantum-well heterostructure material that has hydrolyzed at cleaved edges, cracks, and fissures, and at pinholes in cap layers. The hydrolysis is found to be significant for thicker (〉0.1 μm) AlxGa1−xAs layers of higher composition (x〉0.85).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346527
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  • 8
    Electronic Resource
    Electronic Resource
    The effects of As overpressure and diffusion source on the diffusion of Mn in GaAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5642-5648 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented to show the effect of As overpressure on the diffusion of Mn in GaAs using four different Mn sources. These sources include solid Mn thin film deposited directly on the GaAs substrate and Mn vapors from pure Mn, MnAs, and Mn3As solids. In the circumstance for which a solid Mn film is used as the diffusion source, a nonuniform doping distribution and poor surface morphology is obtained due to a reaction between the Mn film and the GaAs matrix. The degraded surface consists of a layer of polycrystalline cubic alloy having a lattice constant of nearly 8.4 A(ring) and a composition close to MnGa2 with a small amount of As. Of the remaining diffusion sources (Mn, MnAs, and Mn3As), only MnAs consistently produces a uniform doping distribution and smooth surface morphology. For diffusions at 800 °C, a uniform surface hole carrier concentration as high as 1020/cm3 can be obtained using MnAs as the source. The As overpressure is found to drastically alter the Mn diffusion profile, and Mn, like Zn, may diffuse in GaAs interstitial-substitutionally. Vapor from both the Mn and Mn3As solids degrade the GaAs surface. Mn3As, however, uncharacteristically degrades the surface more rapidly although the details of such are not well understood. With the presence of a high As overpressure, however, both surfaces of the Mn and Mn3As sources are converted to (Mn,As) compounds, the compositions being close to MnAs. High enough As overpressures are shown to completely suppress the GaAs surface degradation which is evident when Mn3As alone is used as the diffusion source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351964
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of annealing temperature on the hole concentration and lattice relaxation of carbon-doped GaAs and AlxGa1−xAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5318-5324 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the hole density in carbon-doped GaAs and AlxGa1−xAs as a function of the annealing temperature are presented. It is shown that after sample annealing at low temperatures (T〈550 °C), the hole concentration increases in all samples doped ≥1×1019 cm−3 with a simultaneous decrease in the hole mobility. However, sample annealing at higher temperatures (T(approximately-greater-than)600 °C) results in a reduction of the hole concentration in all samples doped with carbon at concentrations higher than ≈5×1019 cm−3. The reduction in hole concentration is also accompanied by an increase in lattice parameter of the carbon-doped epilayer. The observed changes in the electrical and microstructural properties are explained in terms of two different mechanisms: (1) the passivation of carbon acceptors by the incorporation of hydrogen during growth, and (2) the change in the lattice site location of carbon atoms upon annealing. Direct determination of the lattice site location of carbon in samples doped ≥5×1019 cm−3 showed that the fraction of interstitial carbon after annealing at T(approximately-greater-than)600 °C is at least 70% higher than in the as-grown samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352017
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  • 10
    Electronic Resource
    Electronic Resource
    Surface and bulk leakage currents in transverse junction stripe lasers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1081-1090 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents two ways to reduce leakage currents in transverse junction stripe (TJS) lasers: by reducing surface leakage current and by reducing bulk leakage current. The surface leakage is reduced by treatment with (NH4)2S, while the bulk leakage current is reduced by isoelectronic doping with indium. We report the first detailed experimental investigation on the effect of the chemical treatments on the electrical characteristics and laser thresholds of TJS lasers. Surface treatments of (NH4)2S are demonstrated that reduce surface leakage currents in current injection lasers. After the chemical treatments, a 20-fold reduction in current has been achieved with GaAs/AlGaAs lattice-matched multiple-quantum-well TJS lasers. The laser thresholds of lattice-matched TJS lasers are reduced by 12 mA (or 16%) after the chemical treatments. In addition, InGaAs-GaAs-AlGaAs strained-layer single-quantum-well lasers are treated chemically and a reduction in the laser threshold (10 mA or 14%) is observed. The surface treatments are still effective after 7 days. We also report the first experimental investigation on the effect of isoelectronic In doping on the current-voltage characteristics of Zn-diffused lateral p-n junctions. The trap density in an In-doped AlGaAs layer is reduced by more than one order of magnitude compared to that in an AlGaAs layer without In doping. Bulk leakage currents (shunting currents) in TJS lasers can be reduced by using isoelectronic In doping, which should reduce threshold currents and improve the temperature dependence of TJS lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347375
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