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  • 1
    Electronic Resource
    Electronic Resource
    Molecular beam epitaxy of GaAs/AlGaAs quantum wells on channeled substrates (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 433-435 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/AlGaAs quantum wells (QWs) were grown by molecular beam epitaxy on GaAs (100) substrates patterned with ridges and grooves in the [011¯] direction. Low-temperature cathodoluminescence was used to measure the Al fraction and QW thickness on top of the ridges and grooves as a function of ridge and groove width. Surface diffusion during growth depletes Ga from the side facets while increasing the incorporation of Ga on the (100) sections of ridges and grooves. The QW thickness on top of a ridge grown at 710 °C increases from 72 to 95 A(ring), and the Al fraction x decreases from x=0.33 to x=0.29 as the ridge width is narrowed from 30 to 4 μm. Graded refractive index separate confinement heterostructure lasers with nominally 70 A(ring) QWs and Al0.2Ga0.8As barriers were grown on patterned substrates at 695 and 725 °C. Lasers fabricated on the overgrown 4-μm-wide ridges have a 20 meV decrease in emission energy compared to laser diodes on 30 μm ridges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100943
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  • 2
    Electronic Resource
    Electronic Resource
    Indium adatom migration during molecular beam epitaxial growth of strained InGaAs/GaAs single quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2611-2613 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Indium composition variations in strained InGaAs/GaAs quantum wells grown on nonplanar substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For our growth conditions, the In adatom migration length on (100) facets has been determined to be ∼25 μm. A maximum relative increase of In incorporation of (approximately-equal-to)6% on (100) ridges is observed and is found to be strain independent (In composition) for quantum wells nominally 35 and 70 A(ring) thick with In composition of 0.10–0.22. Significantly asymmetric indium adatom migration is observed between adjacent (100) facets for ridges and grooves formed with (111)A and (311)A multifaceted sidewalls, indicating that multifaceting kinetically inhibits adatom migration. For structures designed for one-step growth of index-guided injection lasers with built-in nonabsorbing waveguides, we show that differences greater than 80 meV in the effective band gap of a 70 A(ring) quantum well can be achieved between the gain region and the nonabsorbing waveguide without relaxing the strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101952
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  • 3
    Electronic Resource
    Electronic Resource
    High-power single-mode AlGaAs lasers with bent-waveguide nonabsorbing etched mirrors (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2131-2135 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nonabsorbing etched mirror structure for AlGaAs single-quantum-well graded-refractive-index separate-confinement heterostructure ridge lasers is analyzed with respect to mirror coupling coefficient, threshold current penalty, and far-field pattern. Measurements of the mirror temperature showed a reduction from 50 to 20 K at 30 mW optical power depending on the degree of overlap of the optical intensity with the absorbing bent-waveguide profile. Pulsed catastrophic optical damage power levels up to 400 mW and a thermally saturated cw power of 165 mW with single-mode operation up to 80 mW have been achieved. Lifetime measurements at 40 mW constant optical power indicated degradation rates ≤10−5/h comparable to AlGaAs lasers with cleaved and coated mirrors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351601
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  • 4
    Electronic Resource
    Electronic Resource
    High-power fundamental mode AlGaAs quantum well channeled substrate laser grown by molecular beam epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1059-1061 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate a high-power AlGaAs single quantum well graded-index separate confinement heterojunction laser grown by molecular epitaxy over channeled substrates. Fundamental mode operation up to 130 mW for reflection modified devices has been achieved at a high differential quantum front-facet efficiency of 81%. This device structure allows extremely low threshold currents to 6 mA for power lasers due to the incorporation of lateral current blocking pn junction by crystallographic plane-dependent doping of amphoteric dopants. We obtained a very high-power continuous-wave fundamental mode operation of this type of laser at extremely low threshold currents and very high overall efficiency of more than 50%. This laser shows considerable potential for applications in optical storage and printer technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101704
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  • 5
    Electronic Resource
    Electronic Resource
    Ga adatom migration over a nonplanar substrate during molecular beam epitaxial growth of GaAs/AlGaAs heterostructures (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 972-974 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thickness variations in GaAs/AlGaAs quantum wells grown on patterned substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For the lower and upper (100) facets joined by an angled (311)A facet, relative increases in quantum well thicknesses up to (approximately-equal-to)6% and 20% are observed, respectively, in the vicinity of the intersection of the facets. Following an exponential behavior, the Ga adatom migration length is found to be in the range of 1–2 μm on both the lower and upper (100) facets and is independent of quantum well thickness. This migration length is orders of magnitude greater than previously reported for Ga adatoms during molecular beam epitaxy growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101693
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  • 6
    Electronic Resource
    Electronic Resource
    Wavelength and threshold current of a quantum well laser in a strong magnetic field (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1827-1829 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The threshold current and the wavelength of a high-power ridge waveguide AlGaAs graded index seperate confinement heterostructure quantum well laser have been studied in strong magnetic fields up to 20 T, to simulate the complete quantum confinement of carriers in a quantum box laser. It will be shown both experimentally and theoretically that the threshold current is increased by the application of a strong magnetic field, while its temperature sensitivity is reduced. It will further be shown that at low temperatures (T〈100 K) laser emission occurs via both free carrier and excitonic transitions, while at higher temperatures (T〉100 K) exciton laser emission is only observed after application of a strong magnetic field, i.e., reduction of the dimensionality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101373
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  • 7
    Electronic Resource
    Electronic Resource
    Investigations on resonant tunneling in III-V heterostructures: Comparison between experimental data and model calculations (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4312-4316 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data obtained on a set of GaAs/AlGaAs double-barrier quantum-well resonant tunneling structures are compared with model calculations of the ideal case where scattering is negligible and tunneling is coherent throughout the entire structure. The comparison points to interface roughness in the well as the most likely cause for the observed large valley currents. The currents at low biases, before resonance sets in, are also studied. Their magnitude is found to be consistent also with the sequential tunneling picture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343977
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  • 8
    Electronic Resource
    Electronic Resource
    Tunneling through asymmetric double-barrier quantum-well heterostructures (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 900-903 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data obtained from a set of asymmetric GaAs/AlGaAs double-barrier resonant tunneling structures is presented. Low-temperature I(V) characteristics, temperature dependencies, and magnetotunneling have been investigated. The data confirm conclusions drawn in previous studies on symmetric structures, lending further support to the description of tunneling in terms of sequential processes and momentum randomization most likely induced by interface roughness scattering in the well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345750
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  • 9
    Electronic Resource
    Electronic Resource
    Doping dependence of the Schottky-barrier height of Ti-Pt contacts to n-gallium arsenide (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1832-1833 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The barrier height and ideality factor of Ti–Pt contacts on n-type GaAs have been measured in the doping range Nd =3.3×1016 to 3×1018 cm−3. The flat-band barrier height, determined from capacitance-voltage measurements, is found to be independent of Nd whereas the effective barrier height for current transport, defined by the relation for thermionic emission, decreases rapidly at Nd 〉1×1018 cm−3. The results agree quite well with thermionic field-emission theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337226
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  • 10
    Electronic Resource
    Electronic Resource
    Correlation of time-resolved electroluminescence and cathodoluminescence measurements on quantum well light emitters with varying barrier widths (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5561-5569 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of a comparative study of the time-dependent luminescence properties of multiple quantum well structures with varying barrier widths which are embedded in the active area of a light-emitting device. The carrier kinetics is investigated by different experimental approaches: Cathodoluminescence and electroluminescence experiments where excitation is on/off-modulated for the purpose of time-resolved measurements and time-resolved electroluminescence experiments in the small signal regime which allow for observation of the carrier kinetics under flatband conditions. Due to the exact determination of the excess carrier density the latter technique provides a sensitive tool for a precise estimation of the mono- and bimolecular recombination coefficients. Comparison with light output data yields radiative and nonradiative parts. We find that coupling of quantum wells dramatically favors nonradiative interface recombination as expected from a theoretical model accounting for the superlattice wavefunctions. On the other hand, the bimolecular recombination rate remains unaltered even when the barrier width is lowered from 18 to 0.9 nm. In contrast, on/off modulated experiments reveal that luminescence decay is strongly influenced by carrier drift out of the active area. A barrier width dependent carrier mobility in growth direction accounts for these results if phonon assisted hopping rather than Bloch transport is presumed. Thus, an estimation of device quality of quantum well light emitters by conventional time-resolved cathodo- (or photo-) luminescence experiments is found to be possible if internal field induced carrier drift processes are taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350193
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