Polarons in the emerging ultra-wide-band-gap semiconductor rutile GeO₂

Polarons are quasiparticles that form when carriers spontaneously self-trap by deforming the lattice through the electron-phonon interaction. The formation of polarons can adversely affect the carrier-transport properites of semiconductors. Compared to their narrower-gap counterparts, ultra-wide-band-gap semiconductors typically exhibit heavier effective masses and reduced electronic screening, factors that can increase the propensity for self-trapping. Here, we investigate the polaronic properites of rutile GeO₂, a semiconductor with an ultra-wide band gap of 4.5 eV that has recently been synthesized n-type and predicted to be p-type dopable. We comment on the impact of polaron formation on the transport properites of rutile GeO₂, and examine its suitability for power-electronics applications.