Band offsets at the interfaces between $\beta$-Ga$_2$O$_3$ and Al$_2$O$_3$

TL;DR

This study uses hybrid functional calculations to determine the band offsets and chemical bonding at interfaces between $eta$-Ga$_2$O$_3$ and various Al$_2$O$_3$ phases, aiding device design.

Contribution

It provides detailed computational analysis of band offsets at $eta$-Ga$_2$O$_3$/Al$_2$O$_3$ interfaces, considering multiple alumina phases and realistic interface models.

Findings

Calculated band offsets for different alumina phases.

Realistic interface models satisfying electron counting rules.

Results useful for $eta$-Ga$_2$O$_3$ device design.

Abstract

The band offsets and the chemical bonding at the interfaces between (-201) $\beta$-Ga$_2$O$_3$ and Al$_2$O$_3$ polymorphs are studied through hybrid functional calculations. For alumina, we consider four representative phases, i.e., $\alpha$, $\kappa$, $\theta$ and $\gamma$-Al$_2$O$_3$. We generate realistic slab models for the interfaces which satisfy electron counting rules. The O atoms bridge the $\beta$-Ga$_2$O$_3$ and Al$_2$O$_3$ slabs and all the dangling bonds are saturated. The band offsets are obtained by applying an alignment scheme which requires separate bulk and interface calculations. The calculated band offsets are useful for the design of devices based on the $\beta$-Ga$_2$O$_3$/Al$_2$O$_3$heterojunctions, particularly $\beta$-Ga$_2$O$_3$ metal-oxide semiconductor field effect transistors.