Electronic properties and stability of M2O3 (M = Al, Ga, In) and alloy (MxGa1‐x)2O3 in α and β phases: A theoretical study

Abstract

AbstractGa2O3 is clearly emerging as an important wide band‐gap semiconductor. Band‐gap engineering is now highly demanded for expanding its applications. Alloying with the same group of metal oxides is a straightforward and effective way. In this work, by using hybrid density functional theory calculations, the structural, electronic properties, and phase stability of group IIIA (Al, Ga, In) metal oxides and their ternary alloys (MxGa1‐x)2O3 (M = Al, In) in the corundum and monoclinic phases are systematically investigated. The lattice constants, elastic constants, modulus, formation energies, band‐gaps, band‐gap deformation potentials, band‐edge alignments, band‐gap bowing, and ternary alloy formation energies are obtained. The basic relations between the geometric structure and electronic properties are discussed. It is found that the cation ordered structure is the most stable alloy structure in the monoclinic phase, rather than the random alloy structure as is commonly thought. A phase stability diagram of the (MxGa1‐x)2O3 alloys is established, showing that the stable phase of the alloy changes from the monoclinic phase to the corundum phase when the incorporation of Al2O3 (In2O3) is greater than 69% (76%). These results can be used to understand the relative experimental data and shed some light on the synthesis and device design efforts of Ga2O3.