Papers by Keyword: Local Vibrational Modes

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Authors: W. Sullivan, John W. Steeds
Abstract: The high-temperature persistent PL defect known as DII is commented on within this study, seen for the first time in low-energy electron irradiated 4H SiC. The local vibrational modes associated with the defect have been identified and the temperature dependence, spatial variation and electron-energy/electron-dose variation of this defect have all been investigated.
Authors: K. Petzke, C. Göbel, Christoph Schrepel, Udo Scherz
Authors: L.I. Murin, V.P. Markevich, J. Lennart Lindström, Mats Kleverman, J. Hermansson, T. Hallberg, Bengt Gunnar Svensson
Authors: Alexander Mattausch, M. Bockstedte, Oleg Pankratov, John W. Steeds, S.A. Furkert, J.M. Hayes, W. Sullivan, Nicolas G. Wright
Abstract: We observe new photoluminescence centers in electron-irradiated 6H-SiC with phonon replicas up to 250 meV and clear threefold isotope splitting of the highest energy mode. Based on ab initio calculations, we discuss the tri-carbon anti-site (C3)Si and the di-interstitial (C2)Hex as models for these centers.
Authors: Valentin V. Litvinov, A.A. Klechko, V.P. Markevich, L.I. Murin, J. Lennart Lindström
Authors: V.P. Markevich, L.I. Murin, J. Lennart Lindström, Masashi Suezawa
Authors: Robert P. Devaty, Fei Yan, Wolfgang J. Choyke, Adam Gali, Tsunenobu Kimoto, Takeshi Ohshima
Abstract: The C-C stretch vibration associated with the dicarbon antisite in 4H SiC has been observed out to the fifth harmonic in the low temperature photoluminescence spectrum. The anharmonicity is accounted for reasonably well by fits to the data based on the Morse potential. We combine the observations from experiment, the analytically tractable Morse potential, and results obtained from first principles calculations on this defect to obtain an estimate of the thermal expansion coefficient of the C-C bond. This local thermal expansion coefficient is considerably smaller than the linear thermal expansion coefficient of bulk 4H SiC, in striking contrast with the recent result for the nitrogen-vacancy center in diamond that the local thermal expansion coefficient is larger than the bulk value.
Authors: K. Petzke, C. Göbel, Christoph Schrepel, P. Thurian, Udo Scherz
Authors: C. Göbel, Christoph Schrepel, Udo Scherz, P. Thurian, G. Kaczmarczyk, Andreas Hoffmann
Authors: Vitor J.B. Torres, J. Coutinho, Patrick R. Briddon
Abstract: We have investigated the hydrogenation of the zinc acceptor in GaP and InP, and of the phosphorus acceptor in ZnTe, by computer modeling. We used a density-functional supercell code and pseudopotentials to deal with the core electrons. However zinc 3d electrons were explicitly taken to be valence electrons. We have determined the relaxed atomic geometry for seven hydrogen sites. We have found that, in the lowest total energy configuration, hydrogen sits in a bond centered position between zinc and arsenic atoms in all GaP, InP and ZnTe semiconductors and is bonded to the phosphorus atom. We found metastable states, by 0.4, 0.4 and 0.5 eV, for structures where H is antibonding to the phosphorus atom for GaP, InP and ZnTe, respectively. The calculated local vibrational modes (LVM) for the bond-centered configuration agree, within 1%, with the experimental values of 2379.0 cm-1 for GaP:Zn-H, 2287.7 cm-1 for InP:Zn-H and 2193 cm-1 for ZnTe:P-H. The isotopic shift due to the replacement of deuterium by hydrogen is reproduced by less than 2.5% using experimental data. The decrease in the LVM when going from GaP to ZnTe, as the perfect bond length increases, is also well-reproduced. A wag mode at 496 cm-1 and lower LVM, a doublet at 329 cm-1 and a singlet at 242 cm-1, are predicted for P-H in ZnTe.
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