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

Abstract

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, ${\mathrm{O}}_{\mathrm{Te}}\text{\ensuremath{-}}\mathrm{H}$ complex, may play an important role in the carrier compensation in CdTe because of its amphoteric character and reasonably high concentration.