A Tight-Binding Model for Gallium Oxide: The Newest Ultra Wide-Bandgap Semiconductor

Ga
2
O
3
, a novel ultra wide-bandgap semiconductor, shows promise for future-generation energy-efficient electronic devices. Ga
2
O
3
presents new challenges when compared with conventional semiconductors due to the presence of polymorphs - structural phases with differing electronic and photonic properties. While modern ab initio electronic structure techniques provide a powerful description of the bulk electronic bandstruc-ture, they become cumbersome when applied to devices and defects. To remedy the need for a compact description of the electronic structure, we develop tight-binding models derived from atomic-orbital and maximally-localized Wannier function bases to describe the valence and conduction band states of the monoclinic and rhombohedral structural phases of Ga
2
O
3
. This model accurately reproduces key features of their electronic structure, a necessary step towards the general description of the functional behaviors of Ga
2
O
3
in heterostructures and devices. This model accurately reproduces low- and high-energy features of the conduction band as well as the bandgap.