The formation of dimers in the gaseous phase of GeTe as a way to fabricate vacancy-free crystalline thin films

Germanium telluride (GeTe) is a multifunctional material with a plethora of useful properties. In particular, it is one of the best thermoelectric materials. Its thermoelectric properties are affected by intrinsic Ge vacancies that are always present in the crystalline phase because of the low formation energy of such defects. This work draws on ab initio molecular dynamics simulations, demonstrating that due to a very special nature of bonding, often called ‘resonant’ and/or ‘metavalent’, the materials evaporate as GeTe dimers rather than individual molecules. We argue that this feature can be used to fabricate oriented vacancy-free GeTe films when the material is thermally evaporated onto a heated templating substrate.