Phonon scattering limited mobility in the representative cubic perovskite semiconductors <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>SrGeO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>BaSnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>
Christian A. Niedermeier, Yu Kumagai, Keisuke Ide, Takayoshi Katase, Fumiyasu Oba, Hideo Hosono, Toshio Kamiya
Abstract
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 ${\mathrm{SrGeO}}_{3}$. $0.5\ifmmode\times\else\texttimes\fi{}0.4\ifmmode\times\else\texttimes\fi{}0.2\text{\ensuremath{-}}\mathrm{m}{\mathrm{m}}^{3}$ large single crystals of the cubic ${\mathrm{SrGeO}}_{3}$ 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 $3.9\ifmmode\times\else\texttimes\fi{}{10}^{2}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$ is obtained, identifying cubic ${\mathrm{SrGeO}}_{3}$ 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 ${\mathrm{SrGeO}}_{3}$, ${\mathrm{BaSnO}}_{3}$, and ${\mathrm{SrTiO}}_{3}$ is provided based on the magnitude of polarization and eigenfrequency of optically active phonons.