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- 1. Lattice Defects in Semiconductors 23, 1-22 (1975) , Institute of Physics, London , “EPR Studies of the Lattice Vacancy and Low-Temperature Damage Processes in Silocon”, G. D. Watkins.EPR studies of silicon irradiated at 20.4 K and 4.2 K by 1.5 MeV and 46 MeV electrons are described. In 46 MeV irradiations the dominant defects formed appear to be divavancies and other multiple defect aggregates which liberate vacancies throughout the anneal to room temperature as they reorder, recombine, etc. For 1.5 MeV irradiations group III atoms play a vital role in p- and n-type materials in trapping interstitials and stabilizing damage. Carbon and oxygen are not effective interstitial traps at these temperatures. Evidence of limited vacancy migration during irradiation is also cited. Two distinct excited configurations of vacancy-oxygen pairs are identified as precursors to A-centre formation in n-type silicon. The kinetics for their conversion to A-centres depends strongly upon the Fermi level as does the isolated vacancy migration energy whhich is measured to be 0.18 ± 0.02 eV for the V= charge state. The vacancy has four charge states, V+, V0, V- and V=. Kinetics for hole release from V+ reveals an activation barrier of 0.057 eV. The concentration of V+ at 20.4 K in boron-doped material indicates the corresponding donor level even closer to the band edge, approximately EV + 0.039 eV. Jahn-Teller energies for V0, V+, and V- are estimated from stress-alignment studies and confirmed to be large. Kinetics studies for reorientation from one Jahn-Teller distortion to another are also described for each charge state.
- 2. Phys. Rev. Lett. 36, 1329 (1976) , “EPR Observation of the Isolated Interstitial Carbon Atom in Silicon ”, G. D. Watkins and K. L. BrowerAn EPR spectrum, labeled Si-G12, is identified as arising from an isolated interstitial carbon atom in silicon. A ?100? C-Si interstitialcy model is suggested for the defect in which a silicon and carbon atom pair partially share single substitutional site. Because carbon is isoelectronic with... (Read more)
- 3. Phys. Rev. B 13, 2511 (1976) , “EPR of a Trapped Vacancy in Boron-Doped Silicon”, G. D. Watkins.An S=1/2 EPR spectrum, labeled Si-G10, is tentatively identified as a lattice vacancy trapped by substitutional boron in silicon. It is produced in boron-doped vacuum floating-zone silicon by 1.5-MeV-electron irradiation at 20.4 K followed by an anneal at ? 180 K, where the isolated vacancy... (Read more)
- 4. Phys. Rev. B 14, 4506 (1976) , “EPR study of neutron-irradiated silicon: A positive charge state of the <100> split di-interstitial”, Young-Hoon Lee, Nikolai N. Gerasimenko, and James W. CorbettThe Si-P6 spectrum shows an intrinsic tetragonal symmetry with the C2 axis along ?100? and distortion forces the principal axes of the g tensor to be displaced in the {100} plane. The g tensor previously identified by Jung and Newell was found to be due to the motionally averaged state... (Read more)
- 5. Solid State Commun. 26, 779-781 (1978) , “Motional effects in the EPR-spectrum of Cu-H-centers in ZnO”, D. ZwingelAt low temperatures, the EPR signal of a Cu2+ center is observed in ZnO single crystals doped both with copper and hydrogen. A clear effect of line narrowing on the copper hfs-lines is observed at T=16K. It is discussed in the model of a Cu-(OH) complex taking into account the thermally induced... (Read more)
- 6. J. Phys. Chem. 83, 3462-3467 (1979) , “Dynamic Interchange among Three States of Phousphorus 4+ in ?-Quartz”, Y. Uchida, J. Isoya, J. A. WeilDynamic averaging due to electron jumping among three states with different sp hybrid directions in the P4+ center [PO4]0 in α-quartz has been studied by single-crystal electron paramagnetic resonance. The spin-Hamiltonian matrices g and Aslp for low temperature (i.e., C140 K) spectra P(І) and P(Ⅱ) and for high temperature spectrum P(A) are reported. For each crystal site, the line positions of P(A) agree well with those derived from the matrices measured for the three states. i.e., with weighted averages including P(І) and the two symmetry-related P(Ⅱ) spectra. (Read more)
- 7. J. Phys. Chem. 88, 5255-5260 (1984) , “Dynamic Interchange among Three States of Phosphorus (4+) in ?-Quartz. 2.”, Y. Uchida, J. Isoya, J. A. WeilThe dynamic process due to electron jumping among three states with different sp hybrid directions in the quasitetrahedral P4+ center [PO4]0 in a-quartz has been investigated by 10-GHz electron paramagnetic resonance, over the temperature range 40 to 400 K. The relative populations (mole fractions ƒІ and ƒІІ) of the ground state P(І) and two degenerate thermally excited states P(ІІ) were determined from the measured EPR absorption line intensity ratios and from the line positions of the averaged state P(A), respectively, in the slow and fast kinetic regions. The temperature dependence of the mole fractions has been explained by considering vibrational sublevels in the potential well describing each state. The jump rate was also obtained, via EPR absorption line-width analysis based on the Bloch equations, in both the slow and the fast regions. The characteristic parameters of the dynamic process, Le., energy separation and vibrational sublevels of the ground and excited states, and barrier height between these, have been determined. (Read more)
- 8. Solid State Commun. 61, 199-202 (1987) , “An EPR study on a new triclinic symmetry defect in neutron-irradiated FZ-silicon”, Wu En, Wu Shu-xian, Mao Jin-Chang, Yan Mao-Xun, Qin Guo-gang
- 9. Physica B 170, 155-167 (1991) , “Electron paramagnetic resonance of hydrogen in silicon ”, Yu.V. Gorelkinskii, N.N. Nevinnyi
- 10. Phys. Rev. Lett. 79, 1507 (1997) , “Identification of the Silicon Vacancy Containing a Single Hydrogen Atom by EPR”, B. Bech Nielsen, P. Johannesen, P. Stallinga, K. Bonde Nielsen
- 11. Phys. Rev. B 59, 12900 (1999) , “Electron-paramagnetic-resonance measurements on the divacancy defect center R4/W6 in diamond”, D. J. Twitchen, M. E. Newton, J. M. Baker, T. R. Anthony, W. F. BanholzerElectron-paramagnetic-resonance (EPR) studies in radiation damaged diamond enriched to 5% 13C have resulted in the identification of the nearest-neighbor divacancy center. It is the isotopic enrichment, and consequent observation of 13C hyperfine lines, that has permitted the... (Read more)
- 12. 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. Dek, N. T. Son, E. JanznThe 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)
- 13. 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. Janzn, 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)
- 14. Phys. Rev. B 74, 134303 (2006) , “1H NMR study of proton dynamics in Cs5H3(SO4)4·xH2O”, Koh-ichi Suzuki and Shigenobu HayashiComplicated phase relations in Cs5H3(SO4)4·xH2O are revealed by thermal analyses. A superprotonic phase transition takes place at 420 K for both the hydrated and the anhydrous forms. The 1H magic-angle-spinning (MAS) NMR... (Read more)
- 15. Phys. Rev. B 74, 155201 (2006) , “Crystal-field theory of Co2+ in doped ZnO”, R. O. Kuzian, A. M. Daré, P. Sati, and R. HaynWe present a crystal-field theory of transition-metal impurities in semiconductors in a trigonally distorted tetrahedral coordination. We develop a perturbative scheme to treat covalency effects within the weak ligand field case (Coulomb interaction dominates over one-particle splitting) and apply... (Read more)
- 16. Phys. Rev. B 74, 235434 (2006) , “Transport properties of n-type ultrananocrystalline diamond films”, I. S. Beloborodov, P. Zapol, D. M. Gruen, and L. A. CurtissWe investigate transport properties of ultrananocrystalline diamond films for a broad range of temperatures. Addition of nitrogen during plasma-assisted growth increases the conductivity of ultrananocrystalline diamond films by several orders of magnitude. We show that films produced at low... (Read more)
- 17. Phys. Rev. B 74, 245219 (2006) , “Dynamics of positively charged muonium centers in indium nitride”, Y. G. Celebi, R. L. Lichti, B. E. Coss, and S. F. J. CoxMuon spin depolarization measurements performed on powdered InN with zero applied magnetic field reveal several positively charged diamagnetic muonium centers. At low temperatures, the Mu+ ground state is weakly relaxing with the characteristics of local tunneling motion, which changes to... (Read more)
- 18. Phys. Rev. Lett. 98, 265502 (2007) , “Monovacancy and Interstitial Migration in Ion-Implanted Silicon”, P. G. Coleman and C. P. BurrowsThe migration of monovacancies (V0) and self-interstitials (I) has been observed in ion-implanted low-doped float-zone silicon by variable-energy positron annihilation spectroscopy. V0 and I were created by the in situ implantation of ~20 keV... (Read more)
- 19. Phys. Rev. B 75, 085415 (2007) , “Positronium as a probe of transient paramagnetic centers in a-SiO2”, D. B. Cassidy, K. T. Yokoyama, S. H. M. Deng, D. L. Griscom, H. Miyadera, H. W. K. Tom, C. M. Varma, and A. P. Mills, Jr.A laser-pump, positron-probe technique has been developed for measuring the dynamics of laser-induced paramagnetic centers in porous materials. The basis of the technique is the fact that the annihilation rate of ortho-positronium may increase in the presence of unpaired spins. By using an intense... (Read more)
- 20. 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
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