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  • 1
    Electronic Resource
    Electronic Resource
    Outgoing multiphonon resonant Raman scattering and luminescence in Be- and C-implanted GaN (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4917-4921 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed outgoing resonant Raman scattering and photoluminescence measurements on as-grown, Be- and C-implanted GaN in the temperature range of 77–330 K. In implanted GaN after postimplantation annealing at 1100 °C, the A1(LO) multiphonons up to the seventh order were observed with the very strong four longitudinal optical (LO) and five LO modes at ∼2955 and ∼3690 cm−1, respectively, showing extraordinary resonance behavior. With the sample temperature, these two modes significantly decreased and increased in intensity, respectively. The phenomenon is attributed to the variation of resonant conditions due to the shift of the band gap energy. Meanwhile, the combination of E2(high) and quasi-LO phonons was strongly enhanced by quasi-LO phonon involvement and thus the corresponding overtones can be clearly observed even up to the sixth order (m=6). The mechanisms that such strong outgoing multiphonon resonance Raman scattering occurred to implanted GaN instead of high-quality as-grown GaN samples can be attributed to the strong Frohlich-induced scattering by LO phonons and exciton-mediated resonant Raman scattering with impurity inducement. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1455682
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  • 2
    Electronic Resource
    Electronic Resource
    Band offsets at the InAlGaAs/InAlAs (001) heterostructures lattice matched to an InP substrate (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5852-5854 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first-principles pseudopotential method combined with virtual crystal approximation is used to calculate band offsets at the In0.53(AlzGa1−z)0.47As/In0.52Al0.48As (001) heterostructures lattice matched to an InP substrate. It is found that the valence-band offset (VBO) varies with respect to the aluminum composition as VBO=0.18–0.16z–0.02z2 eV, while the conduction-band offset (CBO) varies as CBO=0.51–0.33z–0.18z2 eV. Our results are in good agreement with the experimental data. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367443
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  • 3
    Electronic Resource
    Electronic Resource
    Solar-blind AlGaN photodiodes with very low cutoff wavelength (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 403-405 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the fabrication and characterization of AlxGa1−xN photodiodes (x∼0.70) grown on sapphire by low-pressure metalorganic chemical vapor deposition. The peak responsivity for −5 V bias is 0.11 A/W at 232 nm, corresponding to an internal quantum efficiency greater than 90%. The device response drops four orders of magnitude by 275 nm and remains at low response for the entire near-ultraviolet and visible spectrum. Improvements were made to the device design including a semitransparent Ni/Au contact layer and a GaN:Mg cap layer, which dramatically increased device response by enhancing the carrier collection efficiency. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125768
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  • 4
    Electronic Resource
    Electronic Resource
    Band offsets at GaInP/AlGaInP(001) heterostructures lattice matched to GaAs (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1098-1100 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work, the band offsets at the Ga0.5In0.5P/AlxGa0.5−xIn0.5P heterojunction lattice matched to (001) GaAs was calculated over the whole range of aluminum composition from x=0.0 to 0.5 using the first-principles pseudopotential method with virtual crystal approximation. The valence band offset, VBO, varies with x as VBO=0.433x eV, while the inferred conduction band offset CBO at Γ minimum (band-gap difference minus the valence band offset) varies in x as CBOΓ=0.787x eV. Our results are in good agreement with the experimental data. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122096
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  • 5
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    Preparations for the motional Stark effect diagnostic on EASTa) (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-09-04
    Description: Measurement and control of the current profile is essential for high performance and steady state operation of Experimental Advanced Superconducting Tokamak (EAST). For this purpose, a conventional Motional Stark Effect (MSE) diagnostics utilizing photoelastic modulators is proposed and investigated. The pilot experiment includes one channel to verify the feasibility of MSE, whose sightline intersects with Neutral Beam Injection at major radius of R = 2.12 m. A beam splitter is adopted for simultaneous measurements of Stark multiplets and their polarization directions. A simplified simulation code was also developed to explore the Stark splitting spectra. Finally, the filter is optimized based on the viewing geometry and neutral beam parameters.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics (AIP)
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  • 6
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    Magnetoresistance of Au films (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-12-11
    Description: Classical magnetoresistance (MR) in nonmagnetic metals are conventionally understood in terms of the Kohler rule, with violation usually viewed as anomalous electron transport, in particular, as evidence of non-Fermi liquid behavior. Measurement of the MR of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms. Consequently, the Kohler rule should not be used to distinguish normal and anomalous electron transport in solids.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 7
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    Development of the charge exchange recombination spectroscopy and the beam emission spectroscopy on the EAST tokamaka) (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-08-21
    Description: Charge eXchange Recombination Spectroscopy (CXRS) and Beam Emission Spectroscopy (BES) diagnostics based on a heating neutral beam have recently been installed on EAST to provide local measurements of ion temperature, velocity, and density. The system design features common light collection optics for CXRS and BES, background channels for the toroidal views, multi-chord viewing sightlines, and high throughput lens-based spectrometers with good signal to noise ratio for high time resolution measurements. Additionally, two spectrometers each has a tunable grating to observe any wavelength of interest are used for the CXRS and one utilizes a fixed-wavelength grating to achieve higher diffraction efficiency for the BES system. A real-time wavelength correction is implemented to achieve a high-accuracy wavelength calibration. Alignment and calibration are performed. Initial performance test results are presented.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics (AIP)
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