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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5397-5400 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence of the photoluminescent properties of In0.48(AlyGa1−y)0.52P alloys (0≤y≤0.5) on growth temperature and substrate misorientation off GaAs(100) has been studied. Samples were grown using low-pressure metalorganic vapor phase epitaxy. By studying the dependence of ordering behavior in InGaP as a function of substrate misorientation and growth temperature simultaneously, a very large range in low-temperature photoluminescence emission energy—135 meV—has been obtained. The photoluminescence linewidth exhibits a strong, continuous dependence on the extent of atomic ordering (the emission energy) in the alloys. The results indicate that inhomogeneity in the microstructure of the material (i.e., between "ordered'' domains and the "disordered'' matrix) is the dominant photoluminescence broadening mechanism. This investigation has allowed a significant optimization of the optical properties of these materials, including the narrowest low-temperature photoluminescent linewidths reported for all of the In(AlyGa1−y)P alloys exhibiting direct band gaps (4.2 meV for InGaP).
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3041-3045 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal quenching of photoluminescence from InAsxP1−x/InP strained-layer quantum wells has been investigated over the temperature range of 20–295 K. Structures with compositions of x=0.67 and x=1.0 and quantum well thicknesses of 1–17 monolayers were evaluated using Fourier transform photoluminescence spectroscopy. For InAs/InP heterostructures, the activation energy for thermal quenching depended on well thickness. Luminescence quenching was attributed to thermalization of free excitons from the well, and subsequent nonradiative recombination. Addition of phosphorus to the wells alters the recombination process responsible for luminescence quenching.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 405-408 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical emission characteristics of highly strained InAs/InP single quantum wells prepared using atmospheric-pressure organometallic vapor-phase epitaxy have been studied. For well thicknesses of one to three monolayers (ML), the photoluminescence (PL) spectra exhibited intense emission in the energy range 1.15–1.3 eV, with typical full width at half maximum of 8–14 meV. The dependence of PL emission energy on well thickness for 1–5-ML-thick wells was compared with the results of a finite-well calculation, taking into account the effects of strain on the band structure. Good agreement between experiment and theory was obtained for a valence-band offset of 270 meV, consistent with recent reports for the InAs/InP system.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3077-3087 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructures of metalorganic vapor-phase epitaxy alloys of (In,Ga)P grown on GaAs substrates were examined using transmission electron microscopy. Alloys examined were grown at 600–775 °C on substrates at or near (001) or (113)A using growth rates of 0.69 and 0.17 nm/s. Two common semiconductor alloy phenomenon, ordering and phase separation, were studied over this range of growth conditions. The CuPt-type ordering reflections are sharpest for growth at 675 °C and more diffuse at 600 and 725 °C due to higher densities of antiphase boundaries. Order can be eliminated by growth at 750 °C or above to obtain the highest band gaps and optical emission energies. Detailed investigation of the microstructure for growth at 675 °C indicates that ordered domains are platelets consisting of thin (1–2 nm) lamella on (001) planes that alternate between the two {111}B ordering variants, in agreement with a model proposed by others. We have formed "unicompositional'' quantum wells with sharply defined ordered layers between disordered barrier layers by changing growth temperature, which demonstrates that ordering is determined to a great degree by the conditions during growth. Phase separation is seen for the entire range of growth parameters, independently of ordering; its contrast shows modulations with a variable spacing ranging from a few nanometers to ∼100 nm. Implications of the coexistence of phase separation and ordering for growth models describing these phenomena are discussed. © 1995 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1142-1144 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAsxP1−x/InP strained quantum well structures have been prepared by atmospheric-pressure organometallic vapor phase epitaxy (OMVPE). Structures with compositions of x=0.40–0.67 and quantum well thicknesses of 0.8–16 nm were evaluated using photoluminescence spectroscopy. Strain in the pseudomorphic wells ranged from 1.3 to 2.1%. Doublets and multiplets are observed in the photoluminescence spectra and are attributed to luminescence from regions in the wells differing in thickness by a single monolayer, with atomically smooth interfaces over areas greater in lateral extent than the exciton diameter. Typical full widths at half maximum of the photoluminescence from the thinnest wells are 8–14 meV, comparable to the best reported values for thin lattice-matched quantum wells prepared from the InGaAs(P)/InP system using OMVPE.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2616-2618 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe studies of an index-guided ∼4×3 μm2 vertical cavity surface emitting laser with a cw, room temperature 133 μA threshold current and 53% slope efficiency fabricated using selective wet thermal oxidation to provide optical and electrical confinement. While the device operates strictly single mode, a large number of transverse modes are evident in the subthreshold luminescence observed in both vertical and lateral directions. Despite the lumped nature of the index region, the transverse mode wavelengths agree very well with those predicted for a conventional distributed waveguide structure. Waveguide dimensions and an effective index step of 2% between the active and cladding region are determined by fitting the modal data. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 135-137 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The wavelength dependence of the threshold in an InGaP-InAlGaP vertical cavity surface emitting laser is investigated using a microscopic theory of the semiconductor gain medium. Good agreement is found between experiment and theory for the minimum threshold lasing wavelength for a range of laser structures.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1240-1242 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Excitonic transitions in metalorganic vapor phase epitaxially grown InxGa1−xP/In0.48(Al0.7Ga0.3)0.52P strained single quantum-well structures are characterized using low-temperature photoluminescence and photoluminescence excitation (PLE) spectroscopies. The structures consist of several uncoupled quantum wells with thicknesses between 1.2 and 11.3 nm, and compositions x of 0.48 (nominally lattice matched) and 0.56 (∼0.6% biaxial compressive strain). The photoluminescence spectra exhibit intense peaks over the wavelength range 550–650 nm, with linewidths between 7 and 23 meV depending on the well thickness. The PLE spectra reveal strong heavy-hole and light-hole transitions, as well as higher-order (n=2) transitions in the thicker wells. The heavy-hole/light-hole splitting shows little dependence on well thickness in the strained structures, indicating a relatively large conduction band offset of ΔEC∼0.75ΔEG.
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3185-3187 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The phenomenon of ordering in Ga0.52In0.48P is well known to reduce the optical band gap; the amount of band gap reduction is often used to measure the degree of ordering. For such measurements to be meaningful, the band gap of the random ("completely disordered'') binary alloy must be known. Values of this fundamental material parameter appearing in the literature vary by up to 40 meV, while the largest band gap reduction reported to date is only about 120 meV, i.e., within a factor of 3 of the uncertainty in one endpoint. We report here a low temperature band gap of 2.010±0.007 eV for material lattice matched to GaAs as deduced from a broad spectrum of samples believed for different reasons to contain minimal ordering. The corresponding value at 295 K is 1.910±0.008 eV. © 1995 American Institute of Physics.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 587-589 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metalorganic vapor phase epitaxy (MOVPE) is used to grow unicompositional quantum-well (QW) structures, in which the QW and barrier layers are composed of ordered and disordered GaInP, respectively. Transmission electron dark-field micrographs reveal abrupt interfaces between highly ordered QWs and disordered barriers, with no evidence of defect formation. Low-temperature photoluminescence from the structures exhibits relatively broad emission peaks, with emission energy increasing with decreasing QW thickness. The dependence of emission energy on well thickness can be described by a finite square well model only when a type-II band alignment is taken for the heterostructure, in which the conduction band edge of the ordered GaInP QW lies about 135–150 meV below that of the disordered barrier material. These results demonstrate a high degree of control over the ordering process in MOVPE, such that quantum size effects can be realized solely through disorder-order phenomena. Further, the data provide strong support for a type-II (spatially indirect) recombination transition between ordered and disordered GaInP.
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