Computational design of optimal heterostructures for β-Ga₂O₃

Ga₂O₃, a wide-band gap semiconductor, has garnered significant interest for device applications. Many of these applications require the formation of heterostructures to create a conduction-band offset to confine charge carriers. This can be achieved through alloying with Al₂O₃. However, Al₂O₃ has a significantly smaller lattice constant than Ga₂O₃, which introduces strain on the heterostructure. Considering alloys of In₂O₃ and Al₂O₃, we aim to design a heterostructure which closely matches the lattice constant of Ga₂O₃, while maintaining a conduction-band offset.

Using density functional theory with a hybrid functional, we investigate structural and electronic properties of InAlO₃ alloys in the bixbyite, corundum, and monoclinic structures. We find that the lattice constants increase with In concentration. The band gaps decrease with In incorporation, with a bowing parameter of b = 1.98 eV for monoclinic, b = 4.27 eV for corundum, and b = 4.9 eV for bixbyite. Furthermore, our results show that the (In_0.25Al_0.75)₂O₃ monoclinic alloy provides the closest lattice constant match to Ga₂O₃ while possessing a 1 eV conduction-band offset, making it an ideal alloy for heterostructures [1].

[1] S. Seacat et al., arXiv:2310.10557 (2023)