Unifying description of the wurtzite-to-rocksalt phase transition in wide-gap semiconductors: The effect of d electrons on the elastic constants

The mechanism responsible for the wurtzite-to-rocksalt structural phase transition in zinc oxide has been studied through the ab initio calculations of the full phonon properties. We derive a new and general path of the transformation from the parent to the daughter phase which involves an intermediate tetragonal phase. This hypothesis has been tested through analogous calculations on other wide-gap semiconductors, and confirmed in GaN and InN, but not in AlN and SiC. As a consequence of these results, we formulate a general prediction on the effect of d-electrons on the structural and elastic properties of wurtzite semiconductors under pressure.