Properties of (Ga1−xInx)2O3 over the whole x range

Using density-functional ab initio theoretical techniques, we study (Ga1-xInx)2O3 in both its equilibrium structures (monoclinic and bixbyite) and over the whole range of composition. We establish that the alloy exhibits a large and temperature-independent miscibility gap. On the low-x side, the favored phase is isostructural with -Ga2O3; on the high-x side, it is isostructural with bixbyite In2O3. The miscibility gap opens between approximately 15% and 55% In content for the bixbyite alloy grown epitaxially on In2O3, and 15% and 85% In content for the free-standing bixbyite alloy. The gap, volume and band offsets to the parent compound also exhibit anomalies as function of x. Specifically, the offsets in epitaxial conditions are predominantly type-B staggered, but have opposite signs in the two end-of-range phases.