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

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.