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  • 1
    Electronic Resource
    Electronic Resource
    Influence of domain size on optical properties of ordered GaInP2 (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2633-2639 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using dark-field transmission electron microscopy images of ordered GaInP samples, we show how the ordering domain size depends on the growth temperature. Samples with different average domain sizes are compared with regard to their photoluminescence (PL) and excitation spectra. We find a close correlation between the size of the ordered domains and the relative intensity of the PL peak from band–band recombination compared with the rapidly shifting, below-band-gap luminescence emission. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361099
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetoluminescence study on the effective mass anisotropy of CuPtB-ordered GaInP2 alloys (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2814-2817 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence measurements in a magnetic field between 0 and 13.6 T were carried out on CuPtB-ordered GaInP at liquid-helium temperature. Four samples of different degrees of ordering (η, varying from 0 to 0.54) were studied. Experimental results show that the ordering not only induces a band-gap reduction and valence-band splitting, it also causes changes in effective masses and an effective mass anisotropy. By measuring and analyzing the magnetoluminescence with the magnetic field aligned along both ordering (the [1¯11]) and growth (the [001]) directions, we demonstrate that, for the band-edge excitonic state, the reduced mass in the plane perpendicular to the ordering direction is smaller than that in the ordering direction and also smaller than that of a disordered alloy. The exciton binding energy is found nearly independent of the degree of ordering, in agreement with theoretical predictions. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363938
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of free carrier concentration in n-GaInP alloy by Raman scattering (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2515-2519 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360715
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  • 4
    Electronic Resource
    Electronic Resource
    Low-power deposition of fluorinated microcrystalline silicon hydrogen alloy films (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 4024-4027 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fluorinated microcrystalline silicon hydrogen alloy films have been prepared by the radio frequency glow-discharge decomposition of silicon tetrafluoride/hydrogen mixtures. Thereby, μc-Si:F:H films with high dark conductivity (∼10−3 Ω−1 cm−1), high photoconductivity (∼10−4 Ω−1 cm−1), showing crystalline structure in selected-area transmission electron microscope diffraction patterns as well as sharp infrared absorption and Raman shift spectra have been obtained under conditions of low-power density (∼0.15 W cm−2) and hydrogen dilution (∼20%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343432
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of excitons on CdTe solar cells (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8786-8792 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature and doping-level dependence of CdTe solar cells is investigated, taking into account the involvement of excitons on photocurrent transport. We show that the density of excitons in CdTe is comparable with that of minority carriers at doping levels ≥1015 cm−3. From the investigation of the dark-saturation current, we show that the product of electron and hole concentrations at equilibrium is several orders of magnitude more than the square of the intrinsic carrier concentration. With this assumption, we have studied the effect of excitons on CdTe solar cells, and the effect is negative. CdTe solar cell performance with excitons included agrees well with existing experimental results. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373611
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  • 6
    Electronic Resource
    Electronic Resource
    Electroreflectance measurements of electric fields in ordered GaInP2 (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4502-4508 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368675
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  • 7
    Electronic Resource
    Electronic Resource
    Raman scattering studies of chemical-vapor-deposited cubic SiC films of (100) Si (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3176-3186 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman backscattering studies for a series of cubic SiC (3C-SiC) single-crystal films grown on (100)Si by way of chemical vapor deposition (CVD) with SiC film thicknesses dSiC from 600 A(ring) to 17 μm are performed. Raman spectra of samples with dSiC〉4 μm show a sharp and strong feature which obeys the selection rule for the 3C-SiC LO(Γ) phonon line. The Raman signals from the SiC film and the Si substrate show the same polarization behavior which confirms that the crystalline orientations of the Si substrate and 3C-SiC film are the same. Although there is a big lattice mismatch of 20% between 3C-SiC and Si the observed Raman shifts between 3C-SiC/Si and free 3C-SiC films are ≤2 cm−1 and reflect strains of 0.1%–0.2% in films thicker than 4 μm. Some interesting enhancements of Si and 3C-SiC Raman signals are reported. The Si 522 cm−1 phonon from a Si wafer is enhanced in intensity by a factor of 2–3 due to a CVD overlayer of cubic SiC. Furthermore, the 3C-SiC longitudinal optical phonon at the Γ point, LO(Γ), from SiC/Si samples is enhanced by a factor of 2 or 3 following the removal of the Si substrate. The strict selection rules are no longer obeyed in this case. The former is possibly due to the electric-field-induced inelastic scattering from the SiC/Si heterojunction. The latter is explained by the multiple reflection in free 3C-SiC films. Our theoretical analysis shows that if the cross section for forward scattering is about one order of magnitude larger than that for backscattering, this enhancement will appear. The forward scattering has different selection rules from the back scattering and thus could lead to the appearance of the forbidden transverse optical phonon and the depolarization of the 3C-SiC Raman phonons from the SiC free films. The variation of the Raman spectrum with incident power has also been studied. The Raman cross section for 3C-SiC is estimated by a new method. The wavelength shifts of 3C-SiC LO(Γ) phonons taken from SiC/Si or free films are measured and explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341533
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of strain, substrate misorientation, and excitonic transition on the optical polarization of ordered zinc-blende semiconductor alloys (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 6365-6373 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364390
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  • 9
    Electronic Resource
    Electronic Resource
    Band-gap reduction and valence-band splitting of ordered GaInP2 (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2347-2349 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature photoluminescence excitation spectra are used to determine the order-dependent parameters: valence-band splitting and band-gap reduction in spontaneously ordered GaInP2. Effects due to composition fluctuations between different samples and the associated strain, as well as the excitonic binding energies, have been properly taken into account to yield accurate band-gap reduction and valence-band splitting values. The results from recently published ab initio band structure calculations are used to extrapolate the band-gap reduction from the strongest experimentally realized degree of ordering to perfect ordering. We find a total band-gap reduction of 471±12 meV, which is very close to recent theoretical predictions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114340
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  • 10
    Electronic Resource
    Electronic Resource
    Raman spectroscopic investigation of superconducting YBa2Cu3O7−x, semiconducting YBa2Cu3O6+x, and possible impurity phases (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 242-243 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Raman spectroscopic investigation of specimens of superconducting YBa2Cu3O7−x and of the possible impurity phases YBa2Cu3O6+x (semiconductor), Y2BaCuO5, Y2Cu2O5, BaCuO2, CuO, Y2O3, and BaCO3 indicates that in the range 100–700 cm−1, there are six characteristic lines belonging to the superconductor. At 13 K, these lines are at 150, 338, 441, 507, 590, and 644 cm−1. Comparison of the Raman spectra of the superconductor and the semiconductor indicates a mode stiffening of the pair at 338 and 441 cm−1, but a mode softening of the pair at 507 and 590 cm−1. A factor group analysis leads to a tentative assignment of the Raman and infrared allowed modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99651
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