Stability and electronic structure of the low-Σ grain boundaries in CdTe: a density functional study

Using first-principles density functional calculations, we investigate the relative stability and electronic structure of the grain boundaries (GBs) in zinc-blende CdTe. Among the low-Sigma-value symmetric tilt Sigma 3 (111), Sigma 3 (112), Sigma 5 (120), and Sigma 5 (130) GBs, we show that the Sigma 3 (111) GB is always the most stable due to the absence of dangling bonds and wrong bonds. The Sigma 5 (120) GBs, however, are shown to be more stable than the Sigma 3 (112) GBs, even though the former has a higher Sigma value, and the latter is often used as a model system to study GB effects in zinc-blende semiconductors. Moreover, we find that although containing wrong bonds, the Sigma 5 (120) GBs are electrically benign due to the short wrong bond lengths, and thus are not as harmful as the Sigma 3 (112) GBs also having wrong bonds but with longer bond lengths.