A study was made of the structural and electronic properties of various intrinsic and extrinsic defects in CdTe, based upon first-principles calculations. Attention was paid to the role played by these defects in carrier compensation in semi-insulating CdTe. The semi-insulating behavior of CdTe was attributed to the Fermi-level pinning, near to the middle of the band-gap, by deep donors. These deep donors compensated shallow acceptors and were generally assumed to be Te antisites. However, it was found that intrinsic defects, including the Te antisite, might not have a significant effect upon the carrier compensation due either to a lack of deep levels near to the mid-gap or to low defect concentrations. It was instead demonstrated that an extrinsic defect, the OTe–H complex, could play an important role in carrier compensation in CdTe.

Native Defects and Oxygen and Hydrogen-Related Defect Complexes in CdTe - Density Functional Calculations. M.H.Du, H.Takenaka, D.J.Singh: Journal of Applied Physics, 2008, 104[9], 093521