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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Stable single mode operation of grating-surface-emitting laser arrays under frequency-modulated operation (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 756-758 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Direct frequency-modulated operation of ridge-guided linear grating-surface-emitting laser arrays is reported. Simultaneous far-field and spectral measurements of these devices at 1 GHz modulation rates show that both single longitudinal mode and single spatial mode operation are maintained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103412
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  • 5
    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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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Phase separation in InGaN/GaN multiple quantum wells (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1730-1732 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Evidence is presented for phase separation in In0.27Ga0.73N/GaN multiple quantum wells. After annealing for 40 h at a temperature of 950 °C, the absorption threshold at 2.95 eV is replaced by a broad peak at 2.65 eV. This peak is attributed to the formation of In-rich InGaN phases in the active region. X-ray diffraction measurements show a shift in the diffraction peaks toward GaN, consistent with the formation of an In-poor phase. A diffraction peak corresponding to an In-rich phase is also present in the annealed material. Nanoscale In-rich InGaN precipitates are observed by transmission electron microscopy and energy dispersive x-ray chemical analysis. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121166
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  • 8
    Electronic Resource
    Electronic Resource
    Deep level defects in Mg-doped, p-type GaN grown by metalorganic chemical vapor deposition (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3470-3472 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep level defects in Mg-doped, p-type GaN were characterized by deep level transient spectroscopy (DLTS) and photoemission capacitance transient spectroscopy (ODLTS). The measurements were conducted on n+-p junction diodes grown by metalorganic chemical vapor deposition. DLTS revealed discrete deep levels in the lower half of the band gap with activation energies for hole emission of 0.21, 0.39, and 0.41 eV. While DLTS is able to detect deep levels only in the proximity of the valance band edge in p-type, wide band-gap semiconductors, ODLTS enables detection of deep levels throughout the band gap of GaN. The ODLTS spectrum of Mg-doped, p-type GaN is dominated by a deep level with an optical threshold energy for photoionization of ∼1.8 eV. This deep level, which appears to be energetically located near midgap is present in the highest concentration (∼2.4×1015 cm−3) among the deep levels detected in our GaN material. None of the detected deep levels is present in sufficient concentration to significantly compensate the shallow acceptor dopant in our Mg-doped, p-type GaN. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116075
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    High-power (1.4 W) AlGaInP graded-index separate confinement heterostructure visible (λ∼658 nm) laser (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1658-1660 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pulsed operation of an AlGaInP graded-index separate confinement heterostructure laser grown by organometallic vapor phase epitaxy is reported. The laser active region consists of a single 100 A(ring) Ga0.5In0.5P quantum well and 1600 A(ring) graded index regions on both sides of the well. The graded index regions were produced by lattice-matched graded composition (AlyGa1−y)0.5In0.5P quaternary alloys. This structure reduces the broad-area threshold current compared to a double heterostructure laser, with pulsed thresholds as low as 1050 A/cm2. Total pulsed power of 1.4 W at 658 nm is available from an 80 μm×300 μm mesa-stripe laser. A differential quantum efficiency of ∼56% is measured. By examining the cavity length dependence of the threshold current density and quantum efficiency, it is apparent that the quantum well gain has not saturated in these structures. This suggests that devices containing a thinner single quantum well active region may result in a further reduction in threshold current density for visible lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98534
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