Formation and migration of vacancy defects in GeSe and SnSe

The GeSe and SnSe have great potential in nuclear detector devices. Under irradiation, the formation and migration of point defects may affect their properties and performance significantly. In this study, a comparative study of vacancy formation and migration in GeSe and SnSe has been carried out by a first-principles method. It is shown that in both compounds the cation vacancies are much easier to form than anion vacancies, and the cation vacancies are generally easier to migrate than anion vacancies. For both Ge vacancy and Sn vacancy, the migration is anisotropic and the [322] direction is the most favorable migration pathway. The migration energy barrier are 0.54 eV for Ge vacancy and 0.46 ~ 0.52 eV for Sn vacancy, suggesting that vacancy clusters are relatively easy to form in both compounds, which may influence the application of GeSe and SnSe in nuclear detector devices.