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  • 1
    Electronic Resource
    Electronic Resource
    The use of graded InGaAs layers and patterned substrates to remove threading dislocations from GaAs on Si (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2697-2702 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated threading dislocation (TD) removal from GaAs films on Si by introduction of additional InGaAs graded strain layers in combination with growth on patterned substrates. The substrate patterns consisted of mesas with 10–34 μm widths. The mesa sidewalls were either overhanging (concave), leading to free sidewalls for the film on the mesas, or outward sloping (convex) sidewalls with {111} orientation. The dislocation structure was studied using transmission electron microscopy. It was found that the graded strained layers led to a reduction of dislocation density by a factor of ∼5 in films grown both on mesas with concave sidewalls and on unpatterned substrates. This reduction was due to dislocation reactions leading to annihilation of TDs. For films with graded strained layers on mesas with convex sidewalls, an additional factor of ∼3 reduction in TD density was observed in the part of the film that was grown on top of the mesas. In this case all mobile TDs (TDs associated with 60° misfit dislocations, i.e., TDs that could glide to relieve misfit stress) were removed from the film on top of the mesas to the regions above the sidewalls and only TDs associated with 90° misfit dislocations remained. We suggest that this is due to pinning of the TDs associated with 60° misfit dislocations at the mesa edges and we have presented an explanation for this pinning in terms of the stress conditions at the {111} oriented mesa edges. In addition, this leads us to suggest that in order to obtain minimum TD density it is imperative to prevent formation of 90° misfit dislocation during lattice mismatched heteroepitaxial growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357572
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  • 2
    Electronic Resource
    Electronic Resource
    Optimum cavity length for high conversion efficiency quantum well diode lasers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2813-2818 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The cavity length which maximizes the peak power conversion efficiency is determined for quantum well diode lasers. These calculations are based upon simple models of the diode injection laser's electrical and optical behaviors, including saturation in the quantum well gain-current characteristic. Here the influences of the distributed optical cavity loss, electrical resistivity, and facet reflectivity on the optimum cavity length are described. Although a lower facet reflectivity results in increased threshold current, there are advantages to longer devices, as the peak conversion efficiency is not reduced. Since the optimum cavity length is greater for low reflectivity, the diode series resistance is smaller. Furthermore, when operating at the point where conversion efficiency is a maximum, the power output of the device with low facet reflectivity exceeds that of the device with higher facet reflectivity. Therein lies the principle advantage of reduced front-facet reflectivities in high power, high efficiency quantum well diode lasers. Good agreement results when these predictions are applied to a strained InGaAs/AlGaAs single quantum well laser (λ=0.93 μm).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344209
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  • 3
    Electronic Resource
    Electronic Resource
    Optical investigation of organometallic vapor phase epitaxially grown AlxGa1−xP (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6456-6459 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown films of AlxGa1−xP by organometallic vapor phase epitaxy with composition x≤0.8. The electronic and vibrational properties of the alloys were investigated using electrolyte electroreflectance and Raman spectroscopy, respectively. The compositional dependence of the phonon frequencies and electronic transition energies E0 and E1 were evaluated from the measured spectra. There are significant discrepancies between the vibrational frequencies obtained in this experiment and some previous results. The dependence of E0 and E1 on composition is in good agreement with a previous experiment (x≤0.58). However, because of our greater composition range, we have been able to evaluate the nonlinear composition dependence (bowing parameter) for these two transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342061
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  • 4
    Electronic Resource
    Electronic Resource
    Ga0.5In0.5P/GaAs interfaces by organometallic vapor-phase epitaxy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1241-1243 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Organometallic vapor phase epitaxial growth of most III–V compounds is normally performed under group-V-rich conditions, making it difficult to form an abrupt interface during a change of group V species. The Ga0.5In0.5P/GaAs interface is of interest because it offers a potential advantage over AlGaAs/GaAs selectively doped structures by reducing the deep-level donor problem. In this communication, formation of the Ga0.5In0.5P/GaAs interface during low-pressure organometallic vapor phase epitaxial growth is studied by comparing a series of three superlattices grown using different interface formation techniques. Continuous growth, growth stop under group V gas, and growth stop followed by a purge of all reactants are analyzed by Raman scattering, transmission electron microscopy (TEM), and 4-K photoluminescence. All superlattices show good TEM contrast between layers. The growth stop is found to reduce both P and In intermixing into the GaAs layers, relative to the continuously grown superlattice. The purging step further reduces In intermixing, but also results in decomposition of the Ga0.5In0.5P layers, which increases P carryover into the GaAs layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339992
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  • 5
    Electronic Resource
    Electronic Resource
    High-power conversion efficiency in a strained InGaAs/AlGaAs quantum well laser (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3340-3343 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A strained quantum well laser with a front-end power conversion efficiency exceeding 33% under continuous-wave operation is demonstrated. The laser structure, grown by atmospheric pressure organometallic vapor-phase epitaxy, consists of a 70-A(ring) In0.2Ga0.8As quantum well active region with graded index separate confinement heterostructure. Lasing wavelength is 930 nm, and the front-end differential quantum efficiency is 58% for broad-area oxide stripe lasers with a high-reflection coating on the rear facet. Front-end, continuous power outputs greater than 1 W are available. Although these strained quantum well lasers have threshold currents as low as lattice-matched GaAs quantum well lasers, their internal quantum efficiencies appear to be reduced, thus limiting the maximum attainable conversion efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342646
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  • 6
    Electronic Resource
    Electronic Resource
    Coherent continuous wave operation of 10×10×2 grating-surface-emitting diode laser array in a ring configuration (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 7645-7647 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Coherent cw operation of a 10×10×2 grating-surface-emitting diode laser array in a ring configuration is demonstrated. At near twice the threshold current, the ring array exhibits a high degree of spatial coherence (an average of 86%) between emitting grating sections and a narrow linewidth of 28 MHz. The far field fringe visibility is 80% and 88% in the lateral and longitudinal directions, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350363
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrogen passivation of Mg acceptors in GaN grown by metalorganic chemical vapor deposition (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2666-2668 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of the deliberate hydrogenation of GaN were investigated for heteroepitaxial layers grown by metalorganic chemical vapor deposition. The GaN layers were either Mg-doped, p-type after thermal activation, or Si-doped, n type. Elemental depth profiles from secondary ion mass spectroscopy reveal a striking contrast after a deuteration at 600 °C: the deuterium concentration in Mg-doped GaN is ∼1019 cm−3 while there is no detectable deuterium incorporation in the n-type material. Variable temperature Hall effect measurements provide the most direct evidence to date for Mg–H complex formation with the decrease in the hole concentration upon hydrogenation accompanied by an increase in the hole Hall mobility. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114330
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  • 8
    Electronic Resource
    Electronic Resource
    Demonstration of InGaAs/AlGaAs strained-layer distributed-feedback grating-surface-emitting lasers with a buried second-order grating structure (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 228-230 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated InGaAs/AlGaAs strained-layer distributed-feedback grating-surface-emitting lasers with a buried grating structure. The device consists of a pumped distributed-feedback section terminated on both sides by unpumped distributed Bragg reflector sections. cw operation in a stable single longitudinal mode is achieved up to six times threshold. The threshold current density is ∼600 A/cm2. The far-field beam divergence is predominantly single lobed and diffraction limited. The spectral linewidth is 1.0 MHz at an output power of 8 mW.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104697
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  • 9
    Electronic Resource
    Electronic Resource
    Surface-emitting, distributed feedback InGaAs/AlGaAs lasers by organometallic vapor phase epitaxy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4687-4693 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth, fabrication, and operation of InGaAs/AlGaAs distributed feedback (DFB) grating surface emitting (GSE) lasers are described. These devices contain a continuous, buried second-order diffraction grating, for which two organometallic vapor phase epitaxial growths are required. Compared to more conventional distributed Bragg reflector surface emitting lasers, the grating and its coupling coefficient are much more uniform, since it is patterned onto a planar surface. Operation of ten-element linear arrays, and a 10×10 array of DFB-GSEs is also demonstrated, and the threshold dependence on both the layer and array structure is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349060
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  • 10
    Electronic Resource
    Electronic Resource
    Phase separation in InGaN multiple quantum wells annealed at high nitrogen pressures (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3950-3952 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Phase separation was found to occur in In0.33Ga0.67N/GaN multiple-quantum-well structures after annealing at 975 °C in a hydrostatic pressure of 5 kbar N2 for 4 h. X-ray diffraction (XRD) spectra of the as-grown samples showed superlattice peaks that were replaced by a broad, single-phase peak after annealing. Transmission electron microscopy (TEM) images of the annealed samples show In-rich precipitates and voids that are found only within the quantum-well region. Both TEM and XRD measurements indicated that the formation of voids and second phases were suppressed after annealing in a hydrostatic pressure of 15 kbar. In addition, optical absorption measurements on these samples showed no indication of a peak at 2.65 eV that was observed in previous annealing studies. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125504
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