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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of photoluminescence spectra of the pentanary alloy semiconductor (AlxGa1−x)1−zInzPyAs1−y (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3292-3295 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence spectra of the pentanary alloy semiconductor (AlxGa1−x)1−zInzPyAs1−y (x〈0.33, y〈0.18, z〈0.09) are observed at various temperatures between 300 and 13 K. The spectrum at higher temperatures is of a single peak, in which the line shape is well reproduced by an expression of C(E−Eg)1/2 exp[−(E−Eg)/kBT], where E is the photon energy, Eg the band gap, kB Boltzmann constant, and T temperature. At lower temperatures, a band on the lower energy side grows up rapidly. The plot of integrated luminescence intensity of a high-energy peak as a function of reciprocal temperature shows a single exponential slope. The temperature dependence of the peak energy of the high-energy band is of a hyperbolic cotangent form. These experimental results suggest that the peak on the higher-energy side is attributed to a band-to-band transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341501
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  • 2
    Electronic Resource
    Electronic Resource
    Infrared study of amorphous B1−xCx films (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 3392-3400 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous boron carbide (a-B1−xCx) is believed to have an icosahedron-based random network. In this paper, vibrational properties of a-B1−xCx films are studied by IR and Raman spectra, placing particular emphasis on the interpretation of the most prominent 1100-cm−1 band associated with the B–C bond. The 1100-cm−1 band appears in both IR and Raman spectra, and the frequency variation and the intensity as a function of the C content are examined, together with evaluation of the absolute absorption coefficients. Within the framework of the impurity-induced vibration theory, the 1100-cm−1 band is characterized. The estimation of the force constants by the observed frequencies leads to a conclusion that the vibration can be classified as an extrinsic and preferably a local mode. This vibration is well described as the stretching mode of a localized two-center bond between the B and C atoms. In this sense, the C atom in amorphous B1−xCx is not regarded as a network constituent. The frequency shift with the C content supports this conclusion. The absorption intensity of this band exhibits large values for the transverse effective charge of a-B1−xCx. A numeric estimation shows that most part of the observed transverse effective charge comes from the localized charges of the C impurity. This mechanism of the effective charge is consistent with the above argument of frequency. The intrinsic vibrations of the amorphous boron network based on the icosahedron structure reside over the range from 400 to 1000 cm−1 with a small peak at 800 cm−1. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359967
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  • 3
    Electronic Resource
    Electronic Resource
    Raman scattering study of thermal interdiffusion in InGaAs/InP superlattice structures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 204-208 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Interdiffusion process of InGaAs/InP superlattice structures by thermal annealing of 700–850 °C is studied by Raman spectroscopy. Peak intensities and peak energies of InAs-, GaAs-, and InP-like longitudinal optical (LO) phonon modes change with thermal annealing temperature and time. Depth profiles of the group III and group V atoms are estimated quantitatively by measuring the variations of the peak energies of the LO phonon modes and the ratios of the mode intensities. The energy shift of the GaAs-like LO peak showing a small broadening, the existence of nonenergy shift InP LO phonon peak and the emerging of InP-like LO peak in the lower energy region indicate that the interdiffused superlattice consists of uniform compositional InGaAsP well and InP barrier layers and sharp interfaces. It is found that the resulting InGaAsP quaternary alloy is roughly lattice-matched to InP (〈±0.5%). It is also found that the diffusion coefficient in the well region is larger than that in the barrier region, and that the interdiffusion coefficient D0 and activation energy Ea are 8.56×1010 cm2/s and 5.82 eV, respectively. The interdiffusion in this superlattice is determined by the diffusion in the InP region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350310
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  • 4
    Electronic Resource
    Electronic Resource
    Study of Ga ion implantation damage and annealing effect in Sn-doped InP using Raman scattering (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 856-860 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The damage of Sn-doped InP by Ga ion implantation with fluences ranging from 1×1013 to 5×1014 cm−2 and annealing effects (150–650 °C) are investigated by means of Raman scattering. The shift and asymmetrical broadening of a longitudinal optical phonon peak and the appearance of transverse optical mode and disorder-activated acoustic modes show that the damage effect by Ga ion implantation is very large, and the crystalline structure becomes amorphouslike at a fluence as low as 1×1014 cm−2. The damaged state is investigated in terms of the spatial correlation model and quantitatively estimated by comparing the Raman peaks for longitudinal optical and transverse acoustic phonon modes with the theoretical calculations. It is shown that the correlation lengths at 1×1013 cm−2 are 36 and 29 A(ring), respectively. This largely damaged structure is found to be recovered by annealing at as low as 250 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343509
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  • 5
    Electronic Resource
    Electronic Resource
    Simple removal method of diffraction peaks in x-ray absorption fine structure spectra from a single crystal in the fluorescence mode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 25-27 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple method has been proposed for the removal of diffraction peaks from x-ray absorption fine structure spectra of a single crystal observed in the fluorescence mode (i.e., excitation spectrum), in which the diffraction peaks inevitably appear. With a patching up of the appropriate spectrum regions from the spectra having many diffraction peaks, it is shown that we can synthesize one spectrum without the diffraction peaks. Here, several spectra are observed in rotating the single crystal within small angles. As an example, this method is successfully applied in finding the local structure around the Cr3+ ion in a single crystal of α-Al2O3:Cr3+. The bond distances of Cr3+–O2− have been determined as r1=2.04 A(ring) and r2=1.95 A(ring), those are closer to the bond distances in Cr2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144793
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  • 6
    Electronic Resource
    Electronic Resource
    Raman scattering in InGaAlP layers grown by molecular-beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 5007-5011 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman scattering from InGaAlP layers on (100) GaAs substrates grown by molecular-beam epitaxy (MBE) is studied. Compositional dependencies of Raman shifts show two-mode behavior for InAlP and partial three-mode behavior for InGaAlP. The empirical expressions for the compositional variations of LO and TO phonon frequencies are presented. Enhancement of the Raman peak intensities for AlP- and InP-like LO phonons is observed for the composition range when the direct band-gap E0 is close to the photon energy of the excitation light source. The ratio of valley depth to InP-like LO phonon peak height in the Raman spectrum of InGaP ranges from about 0.5 to 0.43, and correlates with the room-temperature photoluminescence peak energy (1.9–1.88 eV). The relationship between these is the same as for the metalorganic vapor-phase epitaxy (MOVPE) samples, although the depth-to-peak height ratios for the MBE samples coincide with the higher side values. The growth temperature dependence is also observed. These results indicate that the InGaP layers grown under the appropriate MBE-growth conditions show the ordered state, although the degree of the order is low. The InAlP layers show Raman spectra having well-resolved InP-like LO and TO phonon peaks. This differs from most of the reported results for MOVPE-grown InAlP layers, and suggests that the MBE-grown InAlP layers are very close to the disordered state alloy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343173
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  • 7
    Electronic Resource
    Electronic Resource
    Raman spectra of the pentanary alloy semiconductor (AlxGa1−x)1−zInzPyAs1−y (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 2160-2162 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Raman scattering of (AlxGa1−x)1−zInzPyAs1−y (x〈0.33, y〈0.18) pentanary alloy semiconductor lattice matched to GaAs is investigated for the first time. Five Raman peaks are found in the composition range studied here, indicating that these materials display the multimode nature in the lattice mode character. The four peaks except the lowest one in frequency are assigned to InAs-, GaAs-, GaP-, and AlAs-like longitudinal optical modes, and the lowest one to disorder activated longitudinal acoustic modes. The other possible two modes, the InP- and AlP-like modes, could not be distinguished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341076
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  • 8
    Electronic Resource
    Electronic Resource
    Raman spectra of AlxIn1−xAs grown by molecular-beam epitaxy (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4632-4634 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman study of the lattice vibrations of a ternary alloy AlxIn1−xAs on InP substrate over the whole range of compositions is reported. The Raman spectra show a two-mode-type behavior involving AlAs- and InAs-like longitudinal optical-phonon modes. The frequency of the AlAs-like mode strongly depends on the composition, but frequency of the InAs-like mode is almost independent of composition. A disorder-induced scattering by acoustic vibrations is also observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339009
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  • 9
    Electronic Resource
    Electronic Resource
    Gas source molecular beam epitaxy growth of short period GaP/AlP(001) superlattices (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1407-1409 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Short period GaP/AlP superlattices are grown on GaP and GaAs substrates at 600 °C by gas source molecular beam epitaxy with growth interruption. Alternating monolayer growth of GaP and AlP is confirmed by the observation of the reflection high-energy electron diffraction intensity oscillations during growth. The formation of short period superlattice structures and the zone-folded LO phonons are observed in the x-ray diffraction rocking curves and Raman spectra, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105207
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  • 10
    Electronic Resource
    Electronic Resource
    XAFS study on metal endohedral fullerenes (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 551-553 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Structure of metal endohedral fullerenes is studied by XAFS and XANES. The Sc-Sc distance of 2.23(1) Å determined from Sc K-edge XAFS supports the formation of a triangular Sc3 cluster in Sc3@C82 as is found by MEM analysis for the X-ray diffraction. Gd LIII-edge XAFS of Gd@C82 shows that the first and the second neigboring Gd-C distances are 2.51(2) and 2.85(4) Å, respectively. The La-La distance of La2@C80 has been determined to be 3.90(1) Å at 40 K. This value does not change when increasing temperature [3.90(2) Å at 240 K]. The position and the valenece of the Eu atom in Eu@C60 are also discussed based on Eu LIII-edge XAFS and XANES.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500017155
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