Metastable structures of cation vacancies in semiconducting oxides

The observed metastable characteristics of cation vacancies in Ga2O3 have prompted a wider search for such systems. In this Perspective, we consider a number of defect systems as candidates for metastability. Some of these are already known to have this property, while for others, this suggestion is new. The examples discussed here are but a sampling of a huge number of systems, and these are used to emphasize that the metastability of defect structures is both common and important; it may yield (for example) split vacancy equilibrium configurations and, hence, should be considered in developing defect models and in analyzing their properties.