Phase diagram and polarization of stable phases of (Ga 1− x In x ) 2 O 3

The full phase diagram of (Ga1-xInx)(2)O-3 is obtained theoretically. The phases competing for the ground state are monoclinic beta (low x), hexagonal (x similar to 0.5), and bixbyite (large x). Three disconnected mixing regions interlace with two distinct phase-separation regions, and at x similar to 0.5, the coexistence of hexagonal and beta alloys with phase-separated binary components is expected. We also explore the permanent polarization of the phases, but none of them are polar. On the other hand, we find that epsilon-Ga2O3, which was stabilized in recent experiments, is pyroelectric with a large polarization and piezoelectric coupling, and could be used to produce high-density electron gases at interfaces. (C) 2016 The Japan Society of Applied Physics