Effective Band Structure and Crack Formation Analysis in Pseudomorphic Epitaxial Growth of (In_xGa_1–x)₂O₃ Alloys: A First-Principles Study

Abstract

Ga 2 O 3 is a promising material for power electronic applications. Alloying with In 2 O 3 is used for band gap adjustment and reduction of the lattice mismatch. In this study, we calculate the effective band structure of 160-atom (In x Ga 1−x ) 2 O 3 supercells generated using special quasi-random structures where indium atoms preferentially substitute octahedral gallium sites in β-Ga 2 O 3 . We find that the disorder has a minimal effect on the lower conduction bands and does not introduce defect states. Employing the Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional, we accurately model the band gap, which remains indirect for all considered indium fractions, x, linearly decreasing from 4.8 to 4.24 eV in the range of x ∈ [0, 0.31]. Accordingly, the electron effective mass also decreases slightly and linearly. We determined the critical thickness for epitaxial growth of the (In Ga ) O x x 1 2 3 alloys over β-Ga 2 O3 surfaces along the [100], [010], and [001] directions. Our findings offer new insights into site preference, effective band structure, and crack formation within (In Ga ) O x x 1 2 3 alloys.