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- 1. phys. stat. sol. (b) 245, 1298-1314 (2008) , “EPR identification of intrinsic defects in SiC”, J. Isoya, T. Umeda, N. Mizuochi, N. T. Son, E. Janzen, T. OhshimaThe structure determination of intrinsic defects in 4H-SiC, 6H-SiC, and 3C-SiC by means of EPR is based on measuring the angular dependence of the 29Si/13C hyperfine (HF) satellite lines, from which spin densities, sp-hybrid ratio, and p-orbital direction can be determined over... (Read more)Si SiC diamond| EPR Theory electron-irradiation thermal-meas./anneal-exp.| +1 -1 0(neutral) 1.0eV~ 13C 29Si C1h C3v Carbon Csi D2d EI5/6 HEI1 HEI9/10 P6/7 Silicon T1 Td Tv2a V1/2/3 Vc Vsi antisite dangling-bond mono(=1) motional-effect n-type p-type pair(=2) quartet semi-insulating spin-relaxation triplet vacancy .inp files: SiC/Baranov/Baranov_g.inp SiC/EI5_C1h/5.inp SiC/EI5_C3v/5.inp SiC/EI6_RT/6.inp SiC/HEI10/HEI10a.inp SiC/HEI10/HEI10b.inp SiC/HEI1_C1h/1.inp SiC/HEI9/HEI9a.inp SiC/HEI9/HEI9b.inp SiC/SI5_C1h/4.inp SiC/Ky2/Ky2.inp SiC/Tv2a/Main.INP SiC/Vsi-_II_4H/Main.INP SiC/Vsi-_II_6H/Main.INP SiC/Vsi-_I_4H/Main.INP SiC/Vsi-_I_6H/Main.INP | last update: Takahide Umeda
- 2. Appl. Phys. Lett. 91, 133507 (2007) , “Identification of atomic-scale defect structure involved in the negative bias temperature instability in plasma-nitrided devices”, J. P. Campbell, P. M. Lenahan, A. T. Krishnan, and S. KrishnanWe utilize a very sensitive electron spin resonance technique called spin-dependent tunneling to identify defect centers involved in the negative bias temperature instability in plasma-nitrided p-channel metal-oxide-silicon field-effect transistors. The defect's 29Si hyperfine... (Read more)
- 3. Phys. Rev. B 75, 245202 (2007) , “Identification of positively charged carbon antisite-vacancy pairs in 4H-SiC”, T. Umeda, J. Ishoya, T. Ohshima, N. Morishita, H. Itoh, and A. GaliAn antisite-vacancy pair and a monovacancy are a set of fundamental stable and/or metastable defects in compound semiconductors. Theory predicted that carbon antisite-vacancy pairs would be much more stable in p-type SiC than silicon vacancies and that they would be a common defect. However,... (Read more)
- 4. Phys. Rev. B 75, 115111 (2007) , “Spin dynamics in a weakly itinerant magnet from 29Si NMR in MnSi”, M. Corti, F. Carbone, M. Filibian, Th. Jarlborg, A. A. Nugroho, and P. Carretta29Si NMR spectra and nuclear spin-lattice relaxation rate measurements in MnSi paramagnetic phase are presented. The experimental results are analyzed in the framework of the self-consistent renormalization theory for spin fluctuations, and detailed estimates of microscopic parameters... (Read more)
- 5. Phys. Rev. B 75, 024109 (2007) , “Optical and EPR properties of point defects at a crystalline silica surface: Ab initio embedded-cluster calculations”, L. Giordano, P. V. Sushko, G. Pacchioni, and A. L. ShlugerWe have studied the structure and spectroscopic properties of the paramagnetic nonbridging oxygen hole center and of the Egamma[prime]" align="middle"> center at the hydroxylated silica surfaces using density functional theory and an embedded-cluster model. To investigate the... (Read more)
- 6. Phys. Rev. Lett. 98, 055504 (2007) , “Ortho-Para Conversion of Interstitial H2 in Si”, M. Hiller, E. V. Lavrov, and J. WeberOrtho-para conversion of isolated interstitial H2 in single-crystalline Si is studied by Raman scattering. This process is suggested to be caused by the interaction of H2 with the nuclear magnetic moment of 29Si. At 77 K the ortho-to-para conversion rate is... (Read more)
- 7. Phys. Rev. B 74, 125203 (2006) , “Density functional theory of structural transformations of oxygen-deficient centers in amorphous silica during hole trapping: Structure and formation mechanism of the Egamma[prime]" align="middle"> center”, T. Uchino and T. YokoWe investigate the hole trapping process of a neutral oxygen vacancy in amorphous silicon dioxide (a-SiO2) using cluster calculations based on the density functional theory (DFT) method. We show that trapping a hole at a neutral oxygen vacancy leads to the formation of several... (Read more)
- 8. Phys. Rev. B 74, 100201(R) (2006) , “Direct spectroscopic observation of the atomic-scale mechanisms of clustering and homogenization of rare-earth dopant ions in vitreous silica”, Sabyasachi Sen, Rafail Rakhmatullin, Ruslan Gubaidullin, and Andreas PöpplStructural aspects of clustering of rare earth ions in oxide glasses have been studied for the last several years in relation to their applications in photonics. However, the mechanism of homogenization of the spatial distribution of rare earth ions by codoping, typically with Al or P, is still not... (Read more)
- 9. Phys. Rev. B 73, 235211 (2006) , “Ab initio calculations for the interconversion of optically active defects in amorphous silica”, M. M. G. Alemany and James R. ChelikowskyUsing ab initio calculations on clusters, we have identified a new reaction path between the dicoordinated silicon atom defect and the paramagnetic Egamma[prime]" align="middle"> center in amorphous silica. Under ionizing irradiation, the dicoordinated silicon atom... (Read more)
- 10. Phys. Rev. Lett. 97, 135502 (2006) , “29Si Hyperfine Structure of the Eα Center in Amorphous Silicon Dioxide”, G. Buscarino, S. Agnello, and F. M. GelardiWe report a study by electron paramagnetic resonance on the Eα point defect in amorphous silicon dioxide (a-SiO2). Our experiments were performed on γ-ray irradiated oxygen-deficient materials and pointed out that the 29Si... (Read more)
- 11. Phys. Rev. Lett. 96, 55501 (2006) , “Divacancy in 4H-SiC”, N. T. Son, P. Carlsson, J. ul Hassan, E. Janzén, T. Umeda, J. Isoya, A. Gali, M. Bockstedte, N. Morishita, T. Ohshima, H. ItohElectron paramagnetic resonance and ab initio supercell calculations suggest that the P6/P7 centers, which were previously assigned to the photoexcited triplet states of the carbon vacancy-antisite pairs in the double positive charge state, are related to the triplet ground... (Read more)
- 12. Phys. Rev. Lett. 96, 145501 (2006) , “Identification of the Carbon Antisite-Vacancy Pair in 4H-SiC”, T. Umeda, N. T. Son, J. Isoya, E. Janzn, T. Ohshima, N. Morishita, H. Itoh, A. Gali, M. BockstedteThe metastability of vacancies was theoretically predicted for several compound semiconductors alongside their transformation into the antisite-vacancy pair counterpart; however, no experiment to date has unambiguously confirmed the existence of antisite-vacancy pairs. Using electron paramagnetic resonance and first principles calculations we identify the SI5 center as the carbon antisite-vacancy pair in the negative charge state (CSiVC-) in 4H-SiC. We suggest that this defect is a strong carrier-compensating center in n-type or high-purity semi-insulating SiC. (Read more)SiC| ENDOR EPR Theory electron-irradiation optical-spectroscopy thermal-meas./anneal-exp.| -1 -2 1.0eV~ 13C 29Si C1h C3v Carbon Csi EI5/6 HEI1 HEI5/6 Nitrogen P6/7 SI5 Silicon Vc antisite bistable/metastable dangling-bond n-type pair(=2) semi-insulating vacancy .inp files: SiC/SI5_C1h SiC/SI5_80K SiC/SI5_100K | last update: Takashi Fukushima
- 13. Phys. Rev. B 72, 235208 (2005) , “Spin multiplicity and charge state of a silicon vacancy (TV2a) in 4H-SiC determined by pulsed ENDOR”, N. Mizuochi, S. Yamasaki, H. Takizawa, N. Morishita, T. Ohshima, H. Itoh, T. Umeda, and J. IsoyaIn this paper, we unambiguously re-determine the spin multiplicity of TV2a by pulsed electron nucleus double resonance technique. The TV2a center is one of the most commonly observed defects in 4H-SiC, and its origin was... (Read more)
- 14. Phys. Rev. B 71, 193202 (2005) , “EPR and theoretical studies of negatively charged carbon vacancy in 4H-SiC”, T. Umeda, Y. Ishitsuka, J. Isoya, N. T. Son, E. Janzén, N. Morishita, T. Ohshima, H. Itoh, A. GaliCarbon vacancies (VC) are typical intrinsic defects in silicon carbides (SiC) and so far have been observed only in the form of positively charged states in p-type or semi-insulating SiC. Here, we present electron-paramagnetic-resonance (EPR) and photoinduced EPR (photo-EPR)... (Read more)
- 15. Phys. Rev. B 71, 125202 (2005) , “Positively charged carbon vacancy in three inequivalent lattice sites of 6H-SiC: Combined EPR and density functional theory study”, V. Ya. Bratus', T. T. Petrenko, S. M. Okulov, and T. L. PetrenkoThe Ky1, Ky2, and Ky3 centers are the dominant defects produced in the electron-irradiated p-type 6H-SiC crystals. The electron paramagnetic resonance study of these defects has been performed in the temperature range of 4.2300 K at... (Read more)
- 16. Phys. Rev. B 71, 115204 (2005) , “Electron Spin Resonance Study of Paramagnetic Centers in Neutron-Irradiated Heat-Treated Silicon”, D. Pierreux and A. StesmansElectron spin resonance (ESR) was used to study neutron-induced defects in silicon as functions of anneal temperature Tan. For Tan below 200 °C, the ESR response is dominated by the Si-P3 and Si-P6 spectra, as observed before. At Tan=200 ... (Read more)
- 17. Appl. Phys. Lett. 84, 3406-3408 (2004) , “Structure of 6H silicon carbide/silicon dioxide interface trapping defects”, David J. Meyer, Nathaniel A. Bohna, and Patrick M. LenahanWe utilize spin-dependent recombination (SDR) to observe deep level trap defects at or very near the interface of 6H silicon carbide and the SiO2 gate dielectric in SiC metal-oxide-semiconductor field effect transistors. The SDR response is strongly correlated to SiC/SiO2... (Read more)
- 18. J. Appl. Phys. 96, 2406-2408 (2004) , “Annealing behavior of the carbon vacancy in electron-irradiated 4H-SiC”, Z. Zolnai, N. T. Son, C. Hallin, and E. JanzénElectron paramagnetic resonance (EPR) was used to study the annealing behavior of the positively charged carbon vacancy (EI5 center) in electron-irradiated 4H-SiC. At ~1000 °C the EPR signal of the defect starts decreasing gradually. Clear ligand hyperfine structure is still observed after... (Read more)
- 19. Mater. Sci. Forum 457-460, 465 (2004) , “EPR and pulsed ENDOR study of EI6 and related defects in 4H-SiC”, T. Umeda, Y. Ishitsuka, J. Isoya, N. Morishita, T. Ohshima, T. Kamiya
- 20. Phys. Rev. B 70, 245204 (2004) , “Silicon vacancy annealing and DI luminescence in 6H-SiC”, M. V. B. Pinheiro, E. Rauls, U. Gerstmann, S. Greulich-Weber, H. Overhof, and J.-M. SpaethCombining electron paramagnetic resonance measurements with ab initio calculations, we identify the VCCSi(SiCCSi) complex as a second annealing product of the silicon vacancy via an analysis of resolved carbon hyperfine interactions and of... (Read more)
- 21. Phys. Rev. B 70, 235212 (2004) , “EPR and theoretical studies of positively charged carbon vacancy in 4H-SiC”, T. Umeda, J. Isoya, N. Morishita, T. Ohshima, T. Kamiya, A. Gali, P. Deák, N. T. Son, E. JanzénThe carbon vacancy is a dominant defect in 4H-SiC, and the "EI5" electron-paramagnetic-resonance (EPR) spectrum originates from positively charged carbon vacancies (VC+) at quasicubic sites. The observed state for EI5, however, has been attributed to a... (Read more)
- 22. Phys. Rev. B 70, 201204(R) (2004) , “Annealing of vacancy-related defects in semi-insulating SiC”, U. Gerstmann, E. Rauls, and H. OverhofThe annealing of P6/P7 centers (VCCSi pairs) in the presence of carbon vacancies in high concentrations typical for semi-insulating (SI) silicon carbide (SiC) is studied theoretically. The calculated hyperfine parameters support the suggestion of a negatively... (Read more)
- 23. Phys. Rev. B 70, 193207 (2004) , “Hyperfine interaction of the nitrogen donor in 4H-SiC”, N. T. Son, E. Janzén, J. Isoya, S. YamasakiShallow N donors in n-type 4H-SiC were studied by electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR). For the N donor at the cubic site (Nk) in 4H-SiC, the hyperfine (hf) constants of the interaction with the nearest-neighbor... (Read more)
- 24. Phys. Rev. B 69, 121201(R) (2004) , “EPR identification of two types of carbon vacancies in 4H-SiC”, T. Umeda, J. Isoya, N. Morishita, T. Ohshima, and T. KamiyaThe EI5 and EI6 centers are typical intrinsic defects in radiation-damaged and semi-insulating 4H-SiC. So far, their origins have been assigned to positively charged carbon vacancies (VC+) and silicon antisites (SiC+), respectively. However,... (Read more)
- 25. Phys. Rev. B 68, 125201 (2003) , “Aggregation of carbon interstitials in silicon carbide: A theoretical study”, A. Gali, P. Deák, P. Ordejón, N. T. Son, E. Janzén, and W. J. ChoykeAb initio supercell calculations have been carried out to investigate clusters of carbon interstitials in 3C- and 4H-SiC. Based on the calculated formation energies, the complex formation of carbon interstitials or their aggregation to carbon antisites is energetically favored... (Read more)
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