Interaction of intrinsic defects with impurities in AI doped ZnSe single crystals

Abstract

We report on the results of a complex study of electrical (77-300 K) and luminescence (10-300 K) properties of n-ZnSe single crystals annealed in a Zn melt containing Al impurity at concentrations ranging from 0.1 to 80 at. %. It was established that Al atoms form donor centers only at a low impurity concentration (≤0.5 at. %). The increase of the amount of Al atoms in the crystal results in the formation of (VZnAlZn) associative acceptor centers leading to the self-compensation of the shallow Al donor impurity. This process is accompanied by the emergence and development of a self-activated luminescence band associated with the (VZnAl Zn) acceptor centers. We show that further increase of the Al content in the melt (≥ 10 at. %) leads to the dissociation of the acceptor complexes and to a recurrent donor doping effect. The photoluminescence spectra of such crystals are dominated by activated luminescence via the (CuznV seCui) and (CuZnAlZn) associative centers. © 2007 American Institute of Physics.