Computational study of Ge and Sn doping of CdTe

Abstract

The formation and ionization energies of substitutional Ge and Sn dopants in CdTe are calculated in a supercell model within the local-density approximation to density-functional theory. Doping on both the Cd and Te sublattices is considered, but the formation energy of both defects is predicted to be much lower on the Cd site under most growth conditions. The Ge and Sn on the Cd sites are predicted to be deep donors and hole traps with defect ionization levels near the midgap, with Ge slightly lower than Sn, in good agreement with experiments. The Ge and Sn on the Te sites are predicted to be shallow acceptors.