Charge transition levels of boron and silicon impurities in GaAs

Full ab-initio Car-Parrinello (CP) calculations have been performed to study effects of defects, vacancies and antisites, as well as various boron sites in silicon doped GaAs. The calculations, which include full relaxation of all ionic coordinates, show that the triple negative gallium vacancy has the minimal formation energy in n-type conducting As-rich GaAs. In p-type semi-insulating As-rich GaAs arsenic antisites are more likely. Furthermore, in boron doped GaAs the acceptor B_Ga^- is predicted to be the dominat defect, while silicon impurities stabalize the B_As^- acceptor by forming (B_AsSi_Ga) complex defects.