AB-INITIO PSEUDOPOTENTIAL CALCULATIONS OF POINT-DEFECTS AND BORON IMPURITY IN SILICON

Ab-initio pseudopotential calculations were performed to obtain the fo rmation energies of point defects in crystalline Si. A supercell of 64 Si atoms was used for the calculations. For the self-interstitial def ect, a weak bond is formed between two defect Si atoms. However, no ev idence of extra bond formation is found in the vacancy study. The form ation energies of both defects are comparable, i.e. 3.7 eV for the vac ancy and 3.25 eV for the self-interstitials, respectively. Our self-in terstitial formation energy agrees well with other theoretical results , while the vacancy formation energy is much smaller. We also present the results of boron substitutional impurities in Si where the charge density plot indicates an ionic character of the B-Si bonding.