Structure of oxygen and silicon interstitials in silicon

The ab initio self-consistent field method and the embedded molecular cluster model (with pseudo-atoms accounting for the crystal environment) containing from 5 to 41 silicon lattice sites were used to investigate the electronic and spatial structure and transport properties of silicon and oxygen interstitials and related defects in silicon. Creation of extended defects (surface layers, amorphous regions, dislocations, etc.) and interaction between point and extended defects in silicon were discussed. The silicon and oxygen interstitial migration activation energies were estimated as 4.21 and 2.73 eV, respectively. The influence of pressure arising, for example, at internal interfaces during O precipitation, was studied. Higher pressure is shown to reduce influence of chemical bonding and to enhance use of free volume during O migration.