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  • 1
    Electronic Resource
    Electronic Resource
    Effects of ordering and alloy phase separation on the optical emission characteristics of In1−xGaxAsyP1−y layers grown on GaAs substrates (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4898-4901 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the optical emission characteristics of low- and high-arsenic content In1−xGaxAsyP1−y alloys grown on exact-oriented (100) GaAs substrates. Clear evidence of a spontaneously ordering superlattice, even in high-arsenic content quaternary samples, was obtained by synchrotron x-ray diffractometry. Photoluminescence measurements at low temperatures revealed the presence of two well-resolved emission bands: an excitation intensity dependent (low-energy) and an excitation intensity independent (high-energy) transitions. Temperature dependent photoluminescence experiments give qualitative information about localization effects of photoexcited carriers in these samples. The origin of carrier localization is attributed to band gap fluctuations in the real space as a result of alloy phase separation and a distribution of domains with varying size and ordering degree. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1360218
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  • 2
    Electronic Resource
    Electronic Resource
    Luminescence and photomodulated transmission measurements in InGaAs/GaAs modulation doped single quantum wells (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3071-3074 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence and photomodulated transmission measurements on In0.2Ga0.8As/ GaAs/Al0.3Ga0.7As modulation doped pseudomorphic single quantum wells are presented. Photomodulated transmission spectra at low temperatures showed sharp lines that are separated with respect to the luminescence peaks due to the Stokes shift. From the Stokes shift we estimated the Fermi energy and the two-dimensional electron gas density. The obtained results are in good agreement with Shubnikov–de-Haas data. The temperature dependence of the optical spectra was also investigated. The photomodulated transmission technique is shown to be a good tool to evaluate the electronic properties of modulation doped single quantum well structures, including an estimation of the Fermi energy and the two-dimensional electron gas density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356155
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  • 3
    Electronic Resource
    Electronic Resource
    Seeding of InP islands on InAs quantum dot templates (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6548-6550 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ability of stacking layers of islands and their corresponding alignment have prompted a number of studies. The main focus so far has been on stacking self-assembled quantum dot (QD) layers of the same material and composition. Our goal is to create systems of coupled QDs of different electronic properties, aiming at hybridization of their different electronic levels. In this work, we investigate the early stages of the coupling of alternate InAs–InP QD layers through a GaAs spacer layer. We have found that by using an InAs layer containing QDs as seeds, we can control the size, shape and density of InP islands by varying the spacer thickness. We have observed a significant improvement of the InP island size uniformity, as well as an induced size reduction, thus providing an extra degree of tunability previously available only through growth kinetics. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1365939
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  • 4
    Electronic Resource
    Electronic Resource
    Photoluminescence microscopy imaging of tensile strained In1−xGaxAsyP1−y/InP quantum wells grown by low-pressure metalorganic vapor phase epitaxy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 402-407 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical properties of tensile strained In1−xGaxAsyP1−y/InP single quantum wells grown by low-pressure metalorganic vapor phase epitaxy were investigated by the real-time integrated photoluminescence microscopy imaging technique at room temperature. The photoluminescence microscopy images revealed the presence of a large number of nonradiative centers (dark spots). The dark spot density was found to be strongly dependent on the tensile strain magnitude, barrier type material and cap layer thickness. High tensile strain values and thin InP cap layers resulted in an increased density of dark spots. Tensile strained structures employing lattice-matched quaternary barriers instead of InP barriers exhibited reduced defect density. Our results indicate that these defects are mainly localized close to or at the interface between the quaternary well and the upper barrier material. The reduction of the number of defects correlates quantitatively with increased radiative recombination efficiency in these structures. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370700
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  • 5
    Electronic Resource
    Electronic Resource
    Photoluminescence of GaAs films grown by vacuum chemical epitaxy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1358-1362 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs layers grown by vacuum chemical epitaxy (VCE) are investigated by low-temperature photoluminescence. A qualitative relation between the growth parameters and the shallow-impurity-incorporation mechanism is established. It was observed that the predominant shallow acceptor is carbon, and its incorporation during the growth process decreases with the As:Ga ratio, increases with growth temperature until 750 °C, and then it diminishes. In this work we compare the characteristics observed in the VCE system with those in conventional molecular-beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Our results show that this system contains some advantages from both the MBE and MOCVD systems. The photoluminescence spectra also show that at low As:Ga ratios the generation of As vacancies or its complexes is strongly enhanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341859
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of barrier alloy composition and number of stacks in the optical and structural characteristics of strain compensated InxGa1−xAsyP1−y/InzGa1−zAstP1−t/InP multiquantum wells (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5915-5922 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have optically and structurally investigated the effect of the barrier alloy composition and number of wells in strain compensated InGaAsP/InP multiquantum well (MQW) samples grown by low-pressure metalorganic vapor phase epitaxy that emit close to 1.55 μm. Low temperature photoluminescence (PL) spectra exhibited two additional anomalous emission lines, below the fundamental QW transition. The PL temperature evolution of such anomalous transitions deviates significantly from the bulk-like band gap behavior expected. Cross-sectional transmission electron microscopy (XTEM) shows that partial elastic relaxation, characterized by localized surface deformations (like surface channels) and/or interfacial undulations occurs for all samples in which anomalous PL lines are observed. TEM results also show that the extra PL lines are correlated to neither Cu–Pt type atomic ordering in the well/barrier layers nor to phase separation. These anomalous transitions are tentatively attributed to the presence of interfacial undulation as well as to surface deformation and to the presence of interfacial domains with an intermediary composition between those of the barrier and QW layers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1467958
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  • 7
    Electronic Resource
    Electronic Resource
    On the origin of Franz–Keldysh oscillations in AlGaAs/GaAs modulation-doped heterojunctions (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5577-5581 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed a series of photoreflectance measurements in a modulation-doped AlGaAs/GaAs heterojunction containing a high mobility two-dimensional electron gas. Measurements were performed as a function of temperature in the range 2 K≤T≤300 K. We studied the Franz–Keldysh oscillations associated with the E0 transition of both the GaAs and AlGaAs. The fields obtained from these oscillations for both sides of the heterojunction are quite different. Also, the temperature dependence of these fields are radically different. In fact, the temperature dependence of the field in the GaAs side of the modulation-doped heterojunction sample is very similar to that of the field in a single undoped GaAs film deposited on a GaAs substrate, where no two-dimensional electron gas is present. This shows that the field producing the observed oscillations on the GaAs side of the modulation-doped heterojunction sample is not related to the field that confines the two-dimensional electron gas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350170
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  • 8
    Electronic Resource
    Electronic Resource
    Photoreflectance measurements on Si δ-doped GaAs samples grown by molecular-beam epitaxy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4149-4151 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate δ-doped GaAs samples grown by molecular-beam epitaxy with different silicon areal concentration and cap layer thickness, using photoreflectance spectroscopy. The features observed on the high-energy side of the fundamental gap are attributed to transitions involving electronic sub-bands in the δ-doped potential well that take into account the diffusion of the dopants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344976
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of barrier recombination on the high temperature performance of quaternary multiquantum well lasers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 67-69 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use spectrally resolved measurements of spontaneous emission to investigate the temperature characteristics of strained and lattice matched InGaAsP multiquantum well lasers. Carrier overflow into the barriers and separate confinement layers and the resulting recombination are demonstrated to be an important factor limiting high temperature performances in these devices. The barrier recombination does not saturate above threshold, instead it increases with the drive current. This effect is further enhanced with increased temperature. We show that the reduction in the barrier recombination correlates quantitatively with increased high temperature slope efficiency. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114185
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  • 10
    Electronic Resource
    Electronic Resource
    State coupling effects in GaAs/InGaAs/AlGaAs modulation doped quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1925-1927 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence and magneto-luminescence techniques were used to evaluate the optical properties of pseudomorphic GaAs/In0.2Ga0.8As/Al0.25Ga0.75As modulation doped single quantum wells. The data are analyzed using self-consistent calculations that predict a strong coupling between the InGaAs quantum well and the potential well formed in the AlGaAs barrier due to planar-doping. The coupling effect gives rise to additional transitions in the emission spectra. Temperature and magnetic field dependence of luminescence spectra provide strong evidence of indirect transitions in these structures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362942
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