Density-functional electronic structure calculations were performed for wurtzite CdS containing native defects and Cu impurity. An investigation was made of the formation energies and ionization levels of the defects in various charge states. The results revealed that the S vacancy was a double donor with the strongly localized orbital at the defect site, and could act as an intrinsic compensation defect under p-type doping. On the other hand, the interstitial S at the tetrahedral site was a double acceptor which formed a dumbbell-like atomic configuration with the nearest S atom. The impurity Cu which replaced Cd produced a single acceptor state, while interstitial Cu generated a single donor state. The calculated formation energies implied that the donor state could also caused compensation in Cu-doped CdS.

Density-Functional Electronic Structure Calculations for Native Defects and Cu Impurities in CdS. K.Nishidate, T.Sato, Y.Matsukura, M.Baba, M.Hasegawa, T.Sasaki: Physical Review B, 2006, 74[3], 035210 (8pp)