Native defects in CdTe

Native defect concentrations in CdTe are calculated from ab initio methods, and compared with experimental results. We examine the native point-defect densities as a function of pressure and temperature in both doped and undoped material. We find that undoped CdTe is highly compensated p type under tellurium-saturated conditions, with the cadmium vacancy as the dominant acceptor and the tellurium antisite as the compensating donor. This finding is in agreement with recent experiments that find a much larger deviation from stoichiometry than would be predicted by the electrically active defects. Under cadmium-saturated conditions, cadmium interstitials are predicted to dominate and the material is found to be n type, resolving the present uncertainty in the identification of this donor. Anneals to produce intrinsic material, and to reduce particular native defects selectively by using extrinsic dopants, are discussed.