Ab InitioStudy of Acceptor-Donor Complexes in Silicon and Germanium

Abstract

The electronic and geometrical structures, in particular the electric field gradients (EFGs), of $[\mathrm{Cd}D{]}^{\ensuremath{-}}$ ( $D\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{P}$, As, Sb) acceptor-donor pairs in Si and Ge are studied using the full potential Korringa-Kohn-Rostoker Green's function method. In addition, also neutral complexes ( $[\mathrm{Cd}D{]}^{0}$) and trimers ( $[\mathrm{Cd}{D}_{2}{]}^{0}$) in Si are investigated. The EFG depends very sensitively on the large lattice relaxations induced by the defects and can be understood by a simple hybridization model. Our calculations are in good agreement with experimental results and provide a consistent picture of acceptor-donor complexes in Si and Ge.