We report the diffusion of boron, arsenic, and phosphorus in silicon isotope multilayer structures at temperatures between 850 °C and 1100 °C. The diffusion of all dopants and self-atoms at a given temperature is modeled with the same setting of all native-point-defect-related parameters.... (Read more)

First-principles plane-wave calculations were performed for hydroxyapatite (HAp) in order to investigate the electronic structure and vacancy formation mechanisms. The HAp unit cell contains PO₄ tetrahedra and OH groups formed by covalent P-O and H-O bonds. Ca ions play a role for... (Read more)

The role of various types of defects in establishing the magnetic properties of the C₆₀-based polymers and the single-wall carbon nanotubes is investigated. Comparing the role of carbon vacancies, and that of substitutional impurity atoms X (X=N, B, O, Si, P, and S) in... (Read more)

First-principles calculations are presented for the phosphorus vacancy V_P in ZnGeP₂, using full-potential linearized muffin-tin orbital supercell local density functional theory calculations. We find the V_P to have a high energy of formation compared to... (Read more)

We propose a new method for calculating optical defect levels and thermodynamic charge-transition levels of point defects in semiconductors, which includes quasiparticle corrections to the Kohn-Sham eigenvalues of density-functional theory. Its applicability is demonstrated for anion vacancies at... (Read more)

Combining efficient density-functional based tight-binding molecular dynamics with ab initio calculations, we show that despite higher formation energies the incorporation of phosphorus at the carbon sublattice is favored by kinetic effects during the annealing processes. Based on the... (Read more)

Using 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)

Two phosphorus centers in SiC, an isolated P atom substituting for Si (P_Si) and a Si-site P-atom adjacent to a carbon vacancy (P_Si+V_C) are investigated by first principle calculations. It is shown that P_Si+V_C produces a singly occupied donor... (Read more)

We have performed the first-principles total-energy calculations on the atomic diffusion of group-V impurities in Si, and have revealed the pressure effect on the activation energy of the diffusion. For the vacancy mechanism, the activation energies for P, As, and Sb decrease with pressure. For the... (Read more)

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 E_V ＋ 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.