Intrinsic Electron Mobility Limits in beta-Ga2O3

TL;DR

This study identifies polar optical phonon scattering as the main factor limiting electron mobility in beta-Ga2O3, providing an empirical model to aid in device design despite its low mobility compared to similar materials.

Contribution

It offers a comprehensive comparison of experimental and theoretical transport properties, revealing the dominant scattering mechanism and presenting an empirical mobility expression for beta-Ga2O3.

Findings

Polar optical phonon scattering limits mobility below 200 cm2/Vs at 300 K.

Electron mobility in beta-Ga2O3 is 10x lower than in GaN due to Frohlich interaction.

An empirical mobility model for beta-Ga2O3 is proposed.

Abstract

By systematically comparing experimental and theoretical transport properties, we identify the polar optical phonon scattering as the dominant mechanism limiting electron mobility in beta-Ga2O3 to lower than 200 cm2/Vs at 300 K for donor doping densities lower than 1018 cm-3. In spite of similar electron effective mass of beta-Ga2O3 to GaN, the electron mobility is 10x lower because of a massive Frohlich interaction, due to the low phonon energies stemming from the crystal structure and strong bond ionicity. Based on the theoretical and experimental analysis, we provide an empirical expression for electron mobility in beta-Ga2O3 that should help calibrate its potential in high performance device design and applications.