A Density‐Functional Study of Oxygen Impurity Complexes in CdTe

Using a first‐principle density functional theory we have calculated the electronic and vibrational structures of two families of oxygen impurities in CdTe: an oxygen atom substituting for Te and an oxygen molecule (O2) located inside a Cd vacancy. The stretching mode frequency of the latter was found to be 1112.5 cm−1 and is infra‐red (IR) active. We suggest that this mode is responsible for the experimentally observed 1104 cm−1 IR absorption peak which has been attributed to a substitutional oxygen plus a neighboring Cd vacancy complex. The band structure calculation suggests that the VCd‐O2 complex behaves like a deep acceptor in CdTe.