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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5110-5113 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The band gap and microstructure of Ga0.5In0.5P have been shown to vary with deposition conditions. However, growth on (511)B GaAs substrates has been reported to give Ga0.5In0.5P with band gaps close to that of disordered material. It is shown here, that with appropriate selection of the growth parameters, Ga0.5In0.5P can be grown with low band gap and significant ordering on even the (511)B substrates, implying that surface steps play an important role in the ordering process. For the lattice-matched composition, a band gap of 1.83 eV was obtained using low growth temperature (575 °C), low growth rate (0.55 μm/h), and high phosphine pressure (5 Torr).
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2515-2519 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of Raman scattering from coupled phonon-plasmon modes in Se-doped n-Ga0.52In048P alloy. Due to the small energy separation between the Γ- and the L-point conduction-band minima for this alloy composition, a significant fraction of the free carriers at room temperature are present in the L-conduction-band valley, giving rise to a multicomponent plasma. The carrier concentrations extracted from the Raman spectra for the different epilayers are in good agreement with the free electron concentrations determined by capacitance-voltage measurements. We employ the light scattering technique to extract the carrier concentration in the n-type emitter layer of a GaInP-based solar cell. © 1995 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 7 (1968), S. 2242-2249 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4502-4508 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ordered Ga0.52In0.48P alloys (GaInP2 for simplicity) grown on miscut [001] GaAs resemble monolayer superlattices with alternating Ga- and In-rich layers along either the [1¯11] or [11¯1] directions. Recent calculations suggest that, in fully ordered GaInP2, an intrinsic ordering-induced electric field of order 1600 kV/cm should exist. In partially ordered samples, as can actually be grown, the expected field is reduced to 400 kV/cm. For such a strong internal electric field, clear Franz–Keldysh Oscillations (FKOs) would be expected in an electroreflectance measurement. We report electroreflectance measurements of ordered GaInP2 layers measured at T=100 K. For all samples measured, no FKOs are observed in the absence of an additional external dc bias voltage. At the lowest bias voltages for which FKOs are seen, the internal electric field in the GaInP2 layer, determined from the FKOs, is ∼60 kV/cm along the [001] direction corresponding to ∼100 kV/cm along the ordering direction. Hence, we conclude that, at least in the organometallic vapor phase epitaxy grown samples studied here, any net macroscopic internal electric field in the GaInP2 layer is less than ∼100 kV/cm along the ordering direction. © 1998 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2780-2787 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In previous work we have identified a near-gap photoluminescence in Ga0.52In0.48P which exhibits a strong dependence of emission energy on excitation intensity ("moving emission'') and correlated its presence and strength to conditions of growth. In this work we extend our investigations to the rise and decay lifetimes associated with the moving and nonmoving components of the emission. The two processes proceed simultaneously at the same energy. For the moving emission, the time constants scale approximately linearly with excitation intensity. Decaying luminescence can, in most cases, be well fitted with one or two exponentials with time constants as long as milliseconds. The rising luminescence is typically slower and in some cases has a nonmonotonic first time derivative. These results are discussed in terms of existing models of the microstructure of ordered Ga0.52In0.48P.
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical polarization in ordered GaInP2 alloys has been studied by low-temperature photoluminescence. A perturbative theory that includes the effects of lattice mismatch, substrate misorientation, and excitonic transitions has been developed for making quantitative comparisons between experimental results and theoretical predictions. We show that to obtain quantitative information about ordering from the polarization of near-band-gap transitions, all of the above-mentioned effects should be taken into account. This study demonstrates that the electronic and optical properties of a monolayer superlattice formed by partial ordering in the GaInP2 alloy can be well described by a simple perturbative Hamiltonian, i.e., a quasicubic model. © 1997 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1890-1895 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Theoretical efficiencies are calculated for two-junction, series-connected solar cells using air mass 1.5 global and direct irradiance spectra. For band-gap combinations previously limited by a low bottom-cell current, thinning of the top cell is shown to result in significant increases in the theoretical efficiencies. The increases are primarily due to increased short-circuit currents, since current matching is achievable. Smaller gains are also seen in the open-circuit voltages of the thinner cells when a low surface-recombination velocity is assumed. Thus, a number of material combinations which previously could only be used in four-terminal configurations can now be considered for series-connected two-junction solar cells.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ordering in the CuPt structure is known to significantly reduce the band gap of Ga0.52In0.48P as well as induce a number of unusual details in its optical properties, including long, excitation-intensity-dependent lifetimes and an excitation-intensity-dependent emission energy. We report photoluminescence (PL), photoluminescence excitation (PLE), and resonant Raman measurements performed on ordered and disordered Ga0.52In0.48P. The dominant high energy emission process at low temperature in disordered Ga0.52In0.48P is established to be excitonic, but the exciton trapping energy is not unique. PLE from ordered Ga0.52In0.48P shows significant tailing of electronic states into the band gap and a "band edge'' which depends on detection energy. The dominant radiative process in ordered Ga0.52In0.48P is not excitonic. A large increase in the Stokes shift between the absorption edge (band gap) and PL emission peak occurs when the material orders. Hence, low temperature PL is determined to be a particularly poor measure of band gap. Resonant Raman scattering is used to study optical phonons and their coupling to electronic states. We find that the resonance enhancement at the band edge occurs via localized excitons.
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 623-625 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two-terminal, monolithic cascade solar cell with an efficiency of 27.3% is reported. The device structure consists of a Ga0.5In0.5P homojunction grown epitaxially upon a GaAs homojunction, with a GaAs tunnel diode interconnect. The tandem combination of these two materials is lattice matched, and has a theoretical efficiency of 34%. The device was grown by metalorganic chemical vapor deposition at 700 °C, using trimethylgallium, trimethylindium, arsine, and phosphine as sources. The minority-carrier transport properties of the Ga0.5In0.5P are shown to be relatively insensitive to variations of the growth temperature and phosphine overpressure. Other factors that affect the efficiency of the device are presented and discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1208-1210 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using time-resolved photoluminescence, we have examined the optoelectronic properties of Ga0.5In0.5P/GaAs/Ga0.5In0.5P double heterostructures grown by organometallic chemical vapor deposition. For comparison, similar structures using Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs lattice-matched heterointerfaces were also examined. For the Ga0.5In0.5P/GaAs heterostructure, we show that the recombination velocity at a Ga0.5In0.5P/GaAs interface can be less than 1.5 cm/s. As a result, photoluminescence decay times as long as 14 μs have been observed in undoped GaAs double heterostructures. This photoluminescence decay time varies with temperature as T1.59, characteristic of radiative recombination not limited by surface or bulk nonradiative recombination processes. For the Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs heterostructures examined in this study, the upper limits of the interface recombination velocity were 210 and 900 cm/s, respectively.
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