Column V acceptors in ZnSe: Theory and experiment

First-principles pseudopotential calculations are used in conjunction with extensive experimental data on P and As-derived acceptor states in ZnSe to develop a microscopic theory of their atomic and electronic properties. A structural model that explains the presence of both shallow and deep acceptor states, the thermal and optical quenching of photoluminescence lines, and the strong C3v symmetry of the electron-spin-resonance (ESR) active state is derived. The primary result of the calculations is that a neutral acceptor possesses two atomic configurations: a metastable effective-mass state with a small lattice relaxation labeled a0, and a deep A0 state with a large lattice distortion which is responsible for most of the observed properties of acceptors in ZnSe. Nitrogen impurities are proposed to give rise to a shallow acceptor state in either the small or large-lattice-relaxed limits. Extension of the results to ZnTe is discussed.