Role of charged oxygen vacancies and substrate lattice constraint on structural stability of Ga2O3 polymorphs

Abstract The effects of charged oxygen vacancies and substrate lattice constraints on the structural stability of Ga 2 O 3 polymorphs are investigated by means of density functional calculations. We find that regardless of crystal phase doubly positively charge sate (V O 2 + ) is stabilized over the wide range of the electron chemical potential. Furthermore, α phase including V O 2 + becomes the most stable for the vacancy concentration larger than 2.8% and the stabilization of α and κ phases compared to that of the β phase are enhanced by the α -Al 2 O 3 (0001) substrate. The results propose one of the physical origins for the growth of the metastable phases in Ga 2 O 3 .