Electron and hole mobility of rutile GeO$_2$ from first principles: an ultrawide-band-gap semiconductor for power electronics

TL;DR

This study uses first-principles calculations to predict electron and hole mobilities in rutile GeO$_2$, revealing its potential as an ultrawide-band-gap semiconductor with superior high-power device performance.

Contribution

First-principles predictions of carrier mobilities in rutile GeO$_2$, highlighting its potential for high-power electronics and surpassing existing semiconductors in performance.

Findings

Electron mobility at 300K: 244-377 cm$^2$/V·s

Hole mobility at 300K: 27-29 cm$^2$/V·s

Baliga figure of merit exceeds Si, SiC, GaN, $eta$-Ga$_2$O$_3$

Abstract

Rutile germanium dioxide (r-GeO$_2$) is a recently predicted ultrawide-band-gap semiconductor with potential applications in high-power electronic devices, for which the carrier mobility is an important material parameter that controls the device efficiency. We apply first-principles calculations based on density functional and density functional perturbation theory to investigate carrier-phonon coupling in r-GeO$_2$ and predict its phonon-limited electron and hole mobilities as a function of temperature and crystallographic orientation. The calculated carrier mobilities at 300 K are $\mu_{\text{elec},\perp \vec{c}}$=244 cm$^2$ V$^{-1}$ s$^{-1}$, $\mu_{\text{elec},||\vec{c}}$=377 cm$^2$ V$^{-1}$ s$^{-1}$, $\mu_{\text{hole},\perp \vec{c}}$=27 cm$^2$ V$^{-1}$ s$^{-1}$, and $\mu_{\text{hole},||\vec{c}}$=29 cm$^2$ V$^{-1}$ s$^{-1}$. At room temperature, carrier scattering is dominated by the low-frequency polar-optical phonon modes. The predicted Baliga figure of merit of n-type r-GeO$_2$ surpasses several incumbent semiconductors such as Si, SiC, GaN, and $\beta$-Ga$_2$O$_3$, demonstrating its superior performance in high-power electronic devices.