Electronic properties of corundum-like Ir₂O₃ and Ir₂O₃-Ga₂O₃ alloys

In the hexagonal, corundum-like structure, $α$-Ga₂O₃ has a bandgap of $∼$ 5.1 eV, which, combined with its relatively small electron effective mass, high Baliga's figure of merit, and high breakdown field, makes it a promising candidate for power electronics. Ga₂O₃ is easy to dope n-type, but impossible to dope p-type, impeding the realization of some electronic device designs. Developing a lattice-matched p-type material that forms a high-quality heterojunction with n-type Ga₂O₃ would open new opportunities in electronics and perhaps optoelectronic devices. In this work, we studied Ir₂O₃ as a candidate for that purpose. Using hybrid density functional theory calculations we predict the electronic band structure of $α$-Ir₂O₃ and compare that to $α$-Ga₂O₃, and study the stability and electronic properties of $α$-(Ir_xGa_1−x)₂O₃ alloys. We discuss the band offset between the two materials and compare it with recently available experimental data. We find that the Ir d bands that compose the top of the valence band in $α$-Ir₂O₃ are much higher in energy than O p bands in $α$-Ga₂O₃, possibly enabling effective p-type doping. Our results provide an insight into using the Ir₂O₃ or Ir₂O₃-Ga₂O₃ alloys as p-type material lattice-matched to $α$-Ga₂O₃ for the realization of p–n heterojunctions.