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- 1. Phys. Rev. B 75, 115418 (2007) , “Early stages of radiation damage in graphite and carbon nanostructures: A first-principles molecular dynamics study”, Oleg V. Yazyev, Ivano Tavernelli, Ursula Rothlisberger, and Lothar HelmUnderstanding radiation-induced defect formation in carbon materials is crucial for nuclear technology and for the manufacturing of nanostructures with desired properties. Using first-principles molecular dynamics, we perform a systematic study of the nonequilibrium processes of radiation damage in... (Read more)
- 2. Phys. Rev. B 75, 085208 (2007) , “Clustering of vacancy defects in high-purity semi-insulating SiC”, R. Aavikko, K. Saarinen, F. Tuomisto, B. Magnusson, N. T. Son, and E. JanzénPositron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the... (Read more)
- 3. Phys. Rev. Lett. 98, 115503 (2007) , “Oxygen Vacancy Clustering and Electron Localization in Oxygen-Deficient SrTiO3: LDA+U Study”, Do Duc Cuong, Bora Lee, Kyeong Mi Choi, Hyo-Shin Ahn, Seungwu Han, and Jaichan LeeWe find, using a local density approximation +Hubbard U method, that oxygen vacancies tend to cluster in a linear way in SrTiO3, a prototypical perovskite oxide, accompanied by strong electron localization at the 3d state of the nearby Ti transition metal ion. The vacancy... (Read more)
- 4. Appl. Phys. Lett. 89, 092113 (2006) , “Large fluorine-vacancy clusters in Si and their capture efficiency for self-interstitials”, Giorgia M. Lopez and Vincenzo FiorentiniBased on ab initio density-functional energetics for saturated (n=2m+2) fluorine-vacancy clusters FnVm for m up to 4, the authors set up a model showing that (a) fluorine-vacancy (FV) aggregates in Si can form in any... (Read more)
- 5. Phys. Rev. B 74, 245420 (2006) , “Energetics, structure, and long-range interaction of vacancy-type defects in carbon nanotubes: Atomistic simulations”, J. Kotakoski, A. V. Krasheninnikov,, and K. NordlundThe presence of vacancy clusters in carbon nanotubes has been assumed to explain the formation of carbon peapods and the difference between the experimentally measured and theoretical fracture strength of nanotubes. We use atomistic simulations at various levels of theory to study the... (Read more)
- 6. Phys. Rev. B 74, 245411 (2006) , “Vacancy defects and the formation of local haeckelite structures in graphene from tight-binding molecular dynamics”, Gun-Do Lee, C. Z. Wang, Euijoon Yoon, Nong-Moon Hwang, and K. M. HoThe dynamics of multivacancy defects in a graphene layer is investigated by tight-binding molecular dynamics simulations and by first principles calculation. The simulations show that four single vacancies in the graphene layer first coalesce into two double vacancies, each consisting of a... (Read more)
- 7. Phys. Rev. B 74, 235201 (2006) , “Annealing of multivacancy defects in 4H-SiC”, W. E. Carlos, N. Y. Garces, E. R. Glaser, and M. A. FantonThe annealing behavior of defects observed in electron paramagnetic resonance (EPR) and photoluminescence (PL) is discussed. We consider the divacancy (the P6/P7 EPR centers) and a previously unreported EPR center that we suggest is a VC-VSi-VC... (Read more)
- 8. Phys. Rev. B 74, 045217 (2006) , “Vacancy clustering and diffusion in silicon: Kinetic lattice Monte Carlo simulations”, Benjamin P. Haley, Keith M. Beardmore, and Niels Grønbech-JensenDiffusion and clustering of lattice vacancies in silicon as a function of temperature, concentration, and interaction range are investigated by kinetic lattice Monte Carlo simulations. It is found that higher temperatures lead to larger clusters with shorter lifetimes on average, which grow by... (Read more)
- 9. Appl. Phys. Lett. 85, 1538 (2004) , “Observation of fluorine-vacancy complexes in silicon”, P. J. Simpson, Z. Jenei, P. Asoka-Kumar, R. R. Robison, M. E. LawWe show direct evidence, obtained by positron annihilation spectroscopy, for the complexing of fluorine with vacancies in silicon. Both float zone and Czochralski silicon wafers were implanted with 30 keV fluorine ions to a fluence of 2×1014 ions/cm2, and studied in the... (Read more)
- 10. Eur. Phys. J. Appl. Phys. 27, 13-19 (2004) , “Measurement of process-induced defects in Si sub-micron devices by combination of EDMR and TEM”, T. Umeda, A. Toda, Y. MochizukiProcess-induced defects are a serious issue for modern sub-micron Si LSIs. To characterize such defects, two different techniques are useful: electrically detected magnetic resonance (EDMR) and transmission electron microscope (TEM), which can detect small (point) and extended defects, respectively. We applied EDMR and TEM to the issue of defect-induced leakage currents in dynamic-random-access memory (DRAM) cells. For our DRAM samples (a 0.25- μm-rule series), although TEM showed no extended defects, EDMR successfully detected two types of point defects: V2+O x (Si divacancy-oxygen complexes) and larger Si vacancies (at least larger than V6). We confirmed that these defects are the source of DRAM leakage currents. The observed defects were formed by ion implantation processes, but were more thermally stable than those in bulk Si crystals. The origins of this enhanced stability are attributed to the presence of oxygen atoms and a strong mechanical strain in LSIs. To clarify the origin of the complicated strain in LSI structures, we can directly measure the local-strain distribution in DRAM samples by means of convergent-beam electron diffraction (CBED) using TEM, which provides us with a valuable hint for understanding the formation mechanism of process-induced defects. (Read more)
- 11. 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)
- 12. Phys. Rev. B 70, 195344 (2004) , “Ab initio study of structural and electronic properties of planar defects in Si and SiC”, C. Raffy, J. Furthmüller, J.-M. Wagner, and F. BechstedtWe present ab initio calculations for internal interfaces in Si and SiC. Density-functional calculations within the local-density approximation and the pseudopotential-plane-wave approach are performed to understand the effect of such two-dimensional defects on the electronic properties. We... (Read more)
- 13. Phys. Rev. B 69, 235202 (2004) , “Ab initio study of the annealing of vacancies and interstitials in cubic SiC: Vacancy-interstitial recombination and aggregation of carbon interstitials”, Michel Bockstedte, Alexander Mattausch, and Oleg PankratovThe annealing kinetics of mobile intrinsic defects in cubic SiC is investigated by an ab initio method based on density-functional theory. The interstitial-vacancy recombination, the diffusion of vacancies, and interstitials to defect sinks (e.g., surfaces or dislocations) as well as the... (Read more)
- 14. Phys. Rev. Lett. 93, 255502 (2004) , “Formation of Thermal Vacancies in Highly As and P Doped Si”, V. Ranki and K. SaarinenUsing positron annihilation measurements we observed the formation of thermal vacancies in highly As and P doped Si. The vacancies start to form at temperatures as low as 650 K and are mainly undecorated at high temperatures. Upon cooling the vacancies form stable vacancy-impurity complexes such as... (Read more)
- 15. Phys. Rev. Lett. 93, 245901 (2004) , “Ab Initio Calculations to Model Anomalous Fluorine Behavior”, Milan Diebel, Scott T. Dunhammplanted fluorine is observed to behave unusually in silicon, manifesting apparent uphill diffusion and reducing diffusion and enhancing activation of boron. In order to investigate fluorine behavior, we calculate the energy of fluorine defect structures in the framework of density functional theory. In addition to identifying the ground-state configuration and diffusion migration barrier of a single fluorine atom in silicon, a set of energetically favorable fluorine defect structures were found (FnVm). The decoration of vacancies and dangling silicon bonds by fluorine suggests that fluorine accumulates in vacancy-rich regions, which explains the fluorine redistribution behavior reported experimentally. (Read more)
- 16. Phys. Rev. B 68, 155208 (2003) , “Theoretical study of vacancy diffusion and vacancy-assisted clustering of antisites in SiC”, E. Rauls, Th. Frauenheim, A. Gali, P. DeákUsing the self-consistent-charge density-functional-based tight-binding (SCC-DFTB) method, we have investigated the migration of vacancies at high temperatures, taking into account the entropy contribution to the Gibbs free energy. We have found that the energy barrier for sublattice migration of... (Read more)
- 17. Phys. Rev. B 67, 205202 (2003) , “Formation and annealing of nitrogen-related complexes in SiC”, U. Gerstmann, E. Rauls, Th. Frauenheim, and H. OverhofWe propose a mechanism for the annealing of vacancy-related defects in SiC, based on ab initio total energy calculations. Our mechanism is based on the formation and migration of carbon and nitrogen split interstitials resulting in CSi(NC)n or... (Read more)
- 18. Phys. Rev. Lett. 90, 155901 (2003) , “Fluorine in Silicon: Diffusion, Trapping, and Precipitation”, X. D. Pi, C. P. Burrows, P. G. ColemanThe effect of vacancies on the behavior of F in crystalline Si has been elucidated experimentally for the first time. With positron annihilation spectroscopy and secondary ion mass spectroscopy, we find that F retards recombination between vacancies (V) and interstitials (I) because V and I trap F to form complexes. F diffuses in the V-rich region via a vacancy mechanism with an activation energy of 2.12±0.08 eV. After a long annealing time at 700ºC, F precipitates have been observed by cross-section transmission electron microscopy which are developed from the V-type defects around the implantation range and the I-type defects at the end of range. (Read more)
- 19. J. Appl. Phys. 90, 6026-6031 (2001) , “Oxygen-Related Defects in Low-Dose Separation-by-Implanted Oxygen Wafers Probed by Monoenergetic Positron Beams”, A. Uedono, Z. Q. Chen, A. Ogura, H. Ono, R. Suzuki, T. Ohdaira, T. Mikado.The depth distributions of oxygen-related defects in separation-by-implanted oxygen wafers were determined from measurements of Doppler broadening spectra of the annihilation radiation. Vacanyoxygen complexes were introduced by implanting 180-keV oxygen at (26)×1017 ... (Read more)
- 20. Phys. Rev. B 63, 245202 (2001) , “Ab initio density-functional supercell calculations of hydrogen defects in cubic SiC”, B. Aradi, A. Gali, P. Deák, J. E. Lowther, N. T. Son, E. Janzén, W. J. ChoykeBased on ab initio density-functional calculations in supercells of 3C-SiC, the stable configurations of hydrogen and dihydrogen defects have been established. The calculated formation energies are used to give semiquantitative estimates for the concentration of hydrogen in SiC after chemical vapor... (Read more)
- 21. Physica B 302-303, 249-256 (2001) , “Hydrogen-Enhanced Clusterization of Intrinsic Defects and Impurities in Silicon”, B. N. Mukashev, Kh. A. Abdullin, Yu. V. Gorelkinskii, M. F. Tamendarov and S. Zh. TokmoldinFormation of intrinsic and impurity defect complexes in hydrogenated monocrystalline silicon is studied. Hydrogen was incorporated into samples by different ways: either by proton implantation at 80 and 300 K, or by annealing at 1250°C for 30–60 min in a sealed quartz ampoule containing... (Read more)
- 22. Mater. Sci. Eng. B 73, 60-63 (2000) , “EPR study of He-implanted Si”, B. Pivac, B. Rakvin, R. Tonini, F. Corni and G. OttavianiElectron paramagnetic resonance has been used to study the influence of thermal treatments on defect evolution in helium-implanted Czochralski single-crystal silicon. It is shown that the thermal treatment induces helium migration and capturing by vacancy clusters that transform into pressurized... (Read more)
- 23. Mater. Sci. Eng. B 71, 249 (2000) , “New (S=1) EPR AA17 center in silicon — microplatelets or precursor of platelets?”, Yu. V. Gorelkinskii, Kh. A. Abdullin, B. N. Mukashev.New (S=1) EPR spectrum (labeled Si-AA17) is observed in irradiated high-purity hydrogen-contained silicon after annealing at ≥200°C. The AA17 defect has D3d symmetry with g=2.0028, g=2.0106; A(29Si)=175.0 MHz, A=89.0 MHz; and D=±33.6 MHz, D=±16.8 MHz. It is paramagnetic in a... (Read more)
- 24. Phys. Rev. B 61, 2657 (2000) , “Divacancy-Tin Complexes in Electron-Irradiated Silicon Studied by EPR”, M. Fanciulli, J. R. Byberg.n- and p-type float-zone silicon containing 1018-cm-3 tin were irradiated with 2 MeV electrons to a dose of 1018 cm-2 and subsequently examined by electron paramagnetic resonance (EPR). The p-type material yields only the well-known Si-G29 signal due to... (Read more)
- 25. Phys. Rev. B 59, 10823-10829 (1999) , “Defect energy levels in electron-irradiated and deuterium-implanted 6H silicon carbide”, M. O. Aboelfotoh, J. P. DoyleUsing deep-level transient spectroscopy, we studied defect energy levels and their annealing behavior in nitrogen-doped 6H-SiC epitaxial layers irradiated with 2-MeV electrons and implanted with 300-KeV deuterium or hydrogen at room temperature. Five levels located at Ec-0.34,... (Read more)
- 26. Physica B 170, 155-167 (1991) , “Electron paramagnetic resonance of hydrogen in silicon ”, Yu.V. Gorelkinskii, N.N. Nevinnyi
- 27. Phys. Rev. B 38, 3395-3399 (1988) , “Electrical and Optical Properties of Defects in Silicon Introduced by High-Temperature Electron Irradiation”, Jian-Guo Xu, Fang Lu, and Heng-Hui Sun2-MeV electron irradiation of Si at elevated temperature creates a dominant deep level at the energy Ec-0.36 eV in addition to the oxygen vacancies. This level, which is less significant in room-temperature-irradiated Si, is found to be an efficient recombination center in the present... (Read more)
- 28. 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
- 29. J. Appl. Phys. 54, 179-183 (1983) , “The Mechanism of the Enhancement of Divacancy Production by Oxygen During Electron Irradiation of Silicon. II. Computer Modeling”, G. S. Oehrlein, I. Krafcsik, J. L. Lindström, A. E. Jaworowski, and J. W. CorbettNumerical tests of possible models for the oxygen dependence of the divacancy introduction rate in silicon electron irradiated at room temperature were performed on a computer. Only the model in which oxygen traps Si self-interstitials can reproduce all the experimental data. Our modeling results... (Read more)
- 30. Phys. Lett. A 99, 117 (1983) , “Low-Symmetry EPR Center in Hydrogen-Implanted Silicon”, Yu.V. Gorelkinskii, N.N. NevinnyiA new S = 1/2 EPR spectrum, labeled Si-AA2, arises from a negative-charge-state defect which has a low symmetry(C1). It is produced in crystalline silicon by hydrogen implantation at ≈20°C followed by annealing at ≈580°C and disappears completely at 700°C. The kinetics... (Read more)Si| EPR ion-implantation| 29Si AA2 C1 Hydrogen Si-H Vsi cluster(>3) p-type triclinic vacancy .inp files: Si/AA2/AA2.inp | last update: Takahide Umeda
- 31. Phys. Rev. B 9, 4351-4361 (1974) , “EPR study of defects in neutron-irradiated silicon: Quenched-in alignment under <110>-uniaxial stress”, Young-Hoon Lee and James W. CorbettThe stress effect in an EPR study is first treated rigorously in terms of the piezospectroscopic tensor, taking account of the local symmetry of a defect. It is found that the degree of alignment (n?/n?) provides incisive information on the structure of a defect; in general, a... (Read more)
- 32. Phys. Rev. B 8, 2810 (1973) , “EPR Studies in Neutron-Irradiated Silicon: A Negative Charge State of a Nonplanar Five-Vacancy Cluster (V5-)”, Y. H. Lee, J. W. Corbett.EPR studies are carried out for the float-zone intrinsic silicon irradiated with reactor neutrons up to the total fluence 1018 n/cm2. Details of the Si29 hyperfine structure and of the g tensor in the P-1 spectrum are observed with respect to temperature from 77 to... (Read more)Si| EPR neutron-irradiation| 29Si P1 Silicon cluster(>3) vacancy .inp files: Si/V5- | last update: Takahide Umeda
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