Structural, electronic, elastic, power and transport properties of $\beta$-Ga$_2$O$_3$ from first-principles

TL;DR

This study uses first-principles calculations to analyze the properties of $eta$-Ga$_2$O$_3$, revealing its electronic, vibrational, and transport characteristics, and assessing its potential for high-power electronic applications.

Contribution

It provides a comprehensive first-principles analysis of $eta$-Ga$_2$O$_3$, including phonon, elastic, and transport properties, and introduces a framework for evaluating high-power electronic materials.

Findings

Room temperature electron mobility of 258 cm$^2$/Vs

Breakdown field of 5.8 MV/cm at room temperature

Baliga's figure of merit of 1250 relative to silicon

Abstract

We investigate the structural, electronic, vibrational, power and transport properties of the $\beta$ allotrope of Ga$_2$O$_3$ from first-principles. We find phonon frequencies and elastic constants that reproduce the correct band ordering, in agreement with experiment. We use the Boltzmann transport equation to compute the intrinsic electron and hole drift mobility and obtain a room temperature values of 258 cm$^2$/Vs and 1.2 cm$^2$/Vs, respectively as well as 6300 cm$^2$/Vs and 13 cm$^2$/Vs at 100 K. Through a spectral decomposition of the scattering contribution to the inverse mobility, we find that multiple longitudinal optical modes of B$_u$ symmetry are responsible for the electron mobility of $\beta$- Ga$_2$O$_3$ but that many acoustic modes also contributes, making it essential to include all scattering processes in the calculations. Using the von Hippel low energy criterion we computed the breakdown field to be 5.8 MV/cm at room temperature yielding a Baliga's figure of merit of 1250 with respect to silicon, ideal for high-power electronics. This work presents a general framework to predictively investigate novel high-power electronic materials.