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  • 1
    Electronic Resource
    Electronic Resource
    Magnetism as a probe for wave function localization in GaSb/AlGaSb quantum wells (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1465-1471 
    Details
    ISSN: 0392-6737
    Keywords: Surface and interface electron states ; Excitons and related phenomena (including electron-hole drops) ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The localization of the wave function on the scale length of a single monolayer has been studied by magnetophotoluminescence in GaSb/AlGaSb quantum wells. The studied range of well width includes the direct-indirect transition involvingL-point conduction states and Γ-point valence states induced by quantum size effects. Separate carrier localization dominates at higher field values (B〉2T), whereas the excitonic effects are important only in the low field range. Variational calculations of the excitonic transverse extension provide a quantitative description of the experimental data. The dependence of the effective reduced mass on the well width has been obtained experimentally by magnetoluminescence that is highly sensitive to the modifications of the wave function, even on the scale of a single monolayer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457228
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  • 2
    Electronic Resource
    Electronic Resource
    Optical spectroscopy at cryogenic temperatures using a Block–Piermarini diamond-anvil cell (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 772-775 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple experimental setup allowing low-temperature high-pressure spectroscopy, with in situ pressure adjustment, is described. A Block–Piermarini diamond-anvil cell is used together with standard laboratory materials. Results of semiconductor photoluminescence studies, using argon as a pressure-transmitting medium, are given as an illustration and are also used for the study of the pressure conditions. Pressure homogeneity is better than 100 MPa up to 6 GPa, and the residual uniaxial component of the stress can be lower than 100 MPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139826
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  • 3
    Electronic Resource
    Electronic Resource
    Band edge versus deep luminescence of InxGa1−xN layers grown by molecular beam epitaxy (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3190-3192 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InxGa1−xN (0〈x〈0.2) thin layers were grown on GaN-coated sapphire substrates by molecular beam epitaxy (MBE) using ammonia as the nitrogen source. Their optical properties have been investigated by low- and room-temperature photoluminescence (PL) and photothermal deflection spectroscopy. It is shown that high-quality InxGa1−xN layers with x∼0.1 can be grown by MBE using NH3. The PL linewidths are 48 and 80 meV at 9 and 300 K, respectively. A bowing parameter of 1 eV is deduced for the band-edge luminescence energy. On the other hand, when the growth conditions slightly move aside the optimum, the PL spectra exhibit broad and deep luminescence. The variation of the PL energy of this deep luminescence as a function of the In composition is then discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121589
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of luminescence self-absorption on photoluminescence decay in GaAs (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5542-5548 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In direct-gap semiconductors, self-absorption processes are known to increase minority carrier lifetimes. In this paper, an original method is developed to solve the dynamic continuity equation with the inclusion of self-absorption phenomena. Also named photo recycling, this process is treated in a model which takes into account the experimental conditions, together with geometrical and optical characteristics of the sample. This method is used to analyze photoluminescence decay experiments on angle-lapped GaAs/Ga0.15Al0.85As double heterostructures. The inclusion of the reabsorption effects is shown to improve the global fit of calculated luminescence with experimental data. This leads to a more accurate determination of key electronic parameters such as diffusion coefficient, surface recombination velocities, and nonradiative lifetime of minority carriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343658
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  • 5
    Electronic Resource
    Electronic Resource
    Buffer free direct growth of GaN on 6H–SiC by metalorganic vapor phase epitaxy (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 577-583 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of GaN on 6H–SiC is three dimensional (3D) and results in the formation of large islands presenting hexagonal truncated shape with {1–101} lateral facets and a top {0001} facet. In this work, we present a three steps growth process that enables us to grow high quality mirrorlike GaN layers without using AlN buffer layers. During a first step, a thin 3D GaN layer is deposited at high temperature. This layer is smoothed under ammonia flow for several minutes when the growth is interrupted. The subsequent growth of GaN is two dimensional. 600 nm thick GaN films were grown. They were analyzed by high resolution x-ray diffraction, reflectivity, and photoluminescence. All the layers are under strong tensile biaxial strain. The correlation between residual tensile strain in GaN layers and their optical properties is reported for biaxial deformations cursive-epsilonxx ranging up to 0.37%. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371902
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature quenching of photoluminescence intensities in undoped and doped GaN (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3721-3728 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work discusses the temperature behavior of the various photoluminescence (PL) transitions observed in undoped, n- and p-doped GaN in the 9–300 K range. Samples grown using different techniques have been assessed. When possible, simple rate equations are used to describe the quenching of the transitions observed, in order to get a better insight on the mechanism involved. In undoped GaN, the temperature dependence of band edge excitonic lines is well described by assuming that the A exciton population is the leading term in the 50–300 K range. The activation energy for free exciton luminescence quenching is of the order of the A rydberg, suggesting that free hole release leads to nonradiative recombination. In slightly p-doped samples, the luminescence is dominated by acceptor related transitions, whose intensity is shown to be governed by free hole release. For high Mg doping, the luminescence at room temperature is dominated by blue PL in the 2.8–2.9 eV range, whose quenching activation energy is in the 60–80 meV range. We also discuss the temperature dependence of PL transitions near 3.4 eV, related to extended structural defects. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371242
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  • 7
    Electronic Resource
    Electronic Resource
    Luminescence and absorption in InGaN epitaxial layers and the van Roosbroeck–Shockley relation (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1525-1534 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Wurtzite InxGa1−xN (0.01(approximately-less-than)x(approximately-less-than)0.14) films have been grown by metalorganic vapor phase epitaxy on sapphire substrates. Integrated photoluminescence intensity and line shapes have been studied as functions of temperature and alloy composition x. We compare the "effective" InGaN band gap energy assessed by photothermal deflection spectroscopy with a "mean" band gap energy calculated from room temperature photoluminescence spectra utilizing the van Roosbroeck–Shockley relation and assuming a Gaussian energy dependence of the subband gap absorption coefficient. The Stokes' shift between band gap energy and 300 K photoluminescence peak is explained by this model. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373850
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  • 8
    Electronic Resource
    Electronic Resource
    Built-in electric-field effects in wurtzite AlGaN/GaN quantum wells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3714-3720 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlGaN/GaN quantum well (QW) structures are grown on c-plane sapphire substrates by molecular beam epitaxy. Control at the monolayer scale of the well thickness is achieved and sharp QW interfaces are demonstrated by the low photoluminescence linewidth. The QW transition energy as a function of the well width evidences a quantum-confined Stark effect due to the presence of a strong built-in electric field. Its origin is discussed in terms of piezoelectricity and spontaneous polarization. Its magnitude versus the Al mole fraction is determined. The role of the sample structure geometry on the electric field is exemplified by changing the thickness of the AlGaN barriers in multiple-QW structures. Straightforward electrostatic arguments well account for the overall trends of the electric-field variations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371241
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  • 9
    Electronic Resource
    Electronic Resource
    Evidence of isovalent impurities in GaAs grown by molecular-beam epitaxy (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 2996-2998 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-pressure, low-temperature photoluminescence spectra of Si-doped GaAs grown by molecular-beam epitaxy show well-defined features corresponding to nitrogen-bound exciton recombination, together with other isoelectronic center-bound excitonlike lines. Though N, when isolated, only influence weakly the GaAs electronic properties, we briefly discuss the consequences of its association with other impurities. It is suggested that complexes involving isovalent impurities may be responsible for part of the defect bound exciton luminescence, observed by several authors in molecular-beam-epitaxy–grown GaAs. The source of isovalent impurities is tentatively attributed to the high-temperature boron nitride crucibles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336919
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  • 10
    Electronic Resource
    Electronic Resource
    From visible to white light emission by GaN quantum dots on Si(111) substrate (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 962-964 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN quantum dots (QDs) in an AlN matrix have been grown on Si(111) by molecular-beam epitaxy. The growth of GaN deposited at 800 °C on AlN has been investigated in situ by reflection high-energy electron diffraction. It is found that a growth interruption performed at GaN thicknesses larger than three molecular monolayers (8 Å) instantaneously leads to the formation of three-dimensional islands. This is used to grow GaN/AlN QDs on Si(111). Depending on their sizes, intense room-temperature photoluminescence is observed from blue to orange. Finally, we demonstrate that stacking of QD planes with properly chosen dot sizes gives rise to white light emission. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124567
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