Carrier compensation in semi-insulating CdTe: First-principles calculations

Carrier compensation in semi- insulating CdTe has been attributed to the compensation of surplus shallow acceptors by deep donors, usually assumed to be Te antisites. However, our first- principles calculations show that intrinsic defects may not have a significant effect on the carrier compensation due either to lack of deep levels near midgap or to low defect concentration. We demonstrate that an extrinsic defect, O-Te-H complex, may play an important role in the carrier compensation in CdTe because of its amphoteric character and reasonably high concentration.