Phonon scattering limited mobility in the representative cubic perovskite semiconductors SrGeO${}_3$, BaSnO${}_3$ and SrTiO${}_3$

Cubic perovskite oxides are emerging high-mobility transparent conducting oxides (TCOs), but Ge-based TCOs had not been known until the discovery of metastable cubic SrGeO${}_3$. $0.5\times 0.4\times 0.2$-mm${}^3$ large single crystals of the cubic SrGeO${}_3$ perovskite were successfully synthesized employing the high-pressure flux method. The phonon spectrum is determined from the IR optical reflectance and Raman-scattering analysis to evaluate the electron transport governed by optical phonon scattering. A calculated room-temperature mobility on the order of $3.9\times {10}^2$ cm${}^2$V${}^{-1}$s${}^{-1}$ is obtained, identifying cubic SrGeO${}_3$ as one of the most promising TCOs. Employing classical phonon theory and a combined experimental-theoretical approach, a comprehensive analysis of the intrinsic electron mobility in the cubic perovskite semiconductors SrGeO${}_3$, BaSnO${}_3$, and SrTiO${}_3$ is provided based on the magnitude of polarization and eigenfrequency of optically active phonons.