To investigate the role of interstitial geometry, ab initio calculations were made of octahedrally and tetrahedrally native interstitials in ZnO, by using the full-potential linear muffin-tin orbital method. The results showed that both zinc interstitials could contribute to the native n-type conduction in ZnO, meanwhile, the zinc vacancy and octahedral O interstitial may contribute to the p-type conduction in ZnO. It was also suggested that the 0.031 and 0.061eV donors, found by temperature-dependent Hall experiments, originated from tetrahedral- and octahedral zinc interstitials, respectively; based upon their charge distribution. It was noticeable that tetrahedral interstitials caused stronger interaction between interstitials and its neighboring atoms than that of octahedral interstitials.

The Electronic Properties of Native Interstitials in ZnO. Sun, Y., Wang, H.: Physica B, 2003, 325, 157-63