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  • 1
    Electronic Resource
    Electronic Resource
    Room-temperature exciton electroabsorption in partially intermixed GaAs/AlGaAs quantum well waveguides (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 534-536 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Perpendicular field electroabsorption is measured for the first time in GaAs/AlGaAs quantum well (QW) structures which have been modified via partial interdiffusion of the well and barrier layers. In waveguide samples containing two GaAs QWs, the impurity-free vacancy diffusion process is shown to allow continuously variable permanent band-edge energy shifts of at least 40 meV while still retaining clearly resolved heavy hole and light hole exciton absorption peaks at room temperature. Furthermore, the quantum-confined Stark effect is shown to be preserved in the partially intermixed structures, greatly expanding the range of photon energies over which such behavior can be utilized in a single epitaxially grown sample. Transmission resonance calculations are used to model the observed enhanced electric-field-induced broadening of exciton absorption peaks in the partially intermixed QWs due to increased carrier tunneling through the graded and lowered potential barriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100922
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  • 2
    Electronic Resource
    Electronic Resource
    Two-dimensional array of high-power strained quantum well lasers with λ=0.95 μm (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2637-2638 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An incoherent, two-dimensional array of high-power lasers operating at λ=0.95 μm is demonstrated. The laser structure consists of a single 70 A(ring) strained In0.2Ga0.8As quantum well active region with an AlGaAs graded-index separate confinement heterostructure, prepared by atmospheric pressure organometallic vapor phase epitaxy. The rack-and-stack array contains 536 oxide-stripe emitter elements in a 1.7 mm×1 cm area, producing approximately 200 Watts at a 60 A drive current. Under pulsed operation the external differential quantum efficiency is 40% while the power conversion efficiency reaches 16%. At high power, greater than 90% of the individual elements are lasing, with an overall spectral width Δλ∼5 mm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101020
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  • 3
    Electronic Resource
    Electronic Resource
    Coherent, monolithic two-dimensional strained InGaAs/AlGaAs quantum well laser arrays using grating surface emission (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2721-2723 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-dimensional coherent strained-layer InGaAs/AlGaAs quantum well laser arrays consisting of 100 (10×10) active elements have been fabricated and characterized. The central lobe of the far field has a full width at half power of 0.04°×1°. Observation of about 2 W peak power from either the substrate or the junction surface, with differential quantum efficiencies from each side of about 40%, is reported. The mode spectrum of the emitted power is contained in a ∼2 A(ring) wavelength interval at ∼2 W.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102256
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  • 4
    Electronic Resource
    Electronic Resource
    Operating characteristics of InGaAs/AlGaAs strained single quantum well lasers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1501-1503 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance of a series of InxGa1−xAs/AlGaAs (x=0.20 and 0.25) strained single quantum well (SSQW) lasers with lasing wavelengths in the range 930≤λ≤1000 nm is discussed. Less-strained devices, with x=0.20 and QW thickness 7 nm (λ∼930 nm), perform comparably with GaAs QW lasers. Longer wavelength (λ〉950 nm), more highly strained lasers exhibit poorer performance. Our results suggest that interfacial recombination limits the performance at the longer wavelength structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101590
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  • 5
    Electronic Resource
    Electronic Resource
    Structural and optical properties of pseudomorphic InxGa1−xN alloys (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1757-1759 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thick (225 nm) InxGa1−xN layers, grown on 5 μm thick GaN, were found by x-ray diffraction (XRD) measurements to be pseudomorphic up to x=0.114. Transmission electron microscopy showed that no misfit or additional threading dislocations were created at the InxGa1−xN/GaN interface. Composition of the overlayers was determined by Rutherford backscattering spectrometry and correlated to both the a and c lattice constants from XRD. It was found that Vegard's law is applicable at these compositions, if the biaxial strain is included. Biaxial strain must also be considered to accurately determine the bowing parameter as shown by optical transmission measurements. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122272
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  • 6
    Electronic Resource
    Electronic Resource
    Continuous, high-power operation of a strained InGaAs/AlGaAs quantum well laser (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2371-2373 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Continuous wave (cw), high-power operation of a strained In0.2Ga0.8As/ AlGaAs quantum well laser, grown by atmospheric pressure organometallic vapor phase epitaxy, is reported. The laser active region consists of a single 70 A(ring) In0.2Ga0.8As/Al0.2Ga0.8As quantum well, with optical confinement provided by a graded index separate confinement heterostructure. The threshold current density and differential quantum efficiency of a 90 μm×600 μm stripe with uncoated facets are ∼200 A/cm2 and 46%, respectively. Lasing wavelength is ∼930 nm, and the cw single ended power versus current characteristic is linear up to 250 mW (1 A current). In the short-cavity (〈300 μm) regime, these devices have high thresholds and have been observed to lase at shorter wavelength, presumably due to a saturation of gain at the lowest energy transition. The characteristic temperature is 150 K and decreases somewhat with cavity length. This suggests that some nonradiative process, most likely Auger recombination, contributes significantly to quantum well gain saturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100233
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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    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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