Spin-orbit coupling and electron scattering in high-quality InSb1−xAsx quantum wells

Abstract

${\mathrm{InSb}}_{1\ensuremath{-}x}{\mathrm{As}}_{x}$ is a promising material system for exploration of topological superconductivity in hybrid superconductor/semiconductor devices due to its large effective $g$-factor and enhanced spin-orbit coupling when compared to binary InSb and InAs. Much remains to be understood concerning the fundamental properties of the two-dimensional electron gas (2DEG) in InSbAs quantum wells. We report on the electrical properties of a series of 30 nm ${\mathrm{InSb}}_{1\ensuremath{-}x}{\mathrm{As}}_{x}$ quantum wells grown 40 nm below the surface with three different arsenic mole fractions, $x=$ 0.05, 0.13, and 0.19. The dependencies of mobility on 2DEG density and arsenic mole fraction are analyzed. For the $x=0.05$ sample, the 2DEG displays a peak mobility $\ensuremath{\mu}=2.4\phantom{\rule{4pt}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{4pt}{0ex}}{10}^{5}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$/Vs at a density of $n=2.5\phantom{\rule{4pt}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{4pt}{0ex}}{10}^{11}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$. High mobility, small effective mass, and strong spin-orbit coupling result in beating in the Shubnikov de Haas oscillations at low magnetic field. Fourier analysis of the Shubnikov de Haas oscillations facilitates extraction of the Rashba spin-orbit parameter $\ensuremath{\alpha}$ as a function of 2DEG density and quantum well mole fraction. For $x=0.19$ at $n=3.1\phantom{\rule{4pt}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{4pt}{0ex}}{10}^{11}$ cm ${}^{\ensuremath{-}2}$, $\ensuremath{\alpha}\ensuremath{\approx}300$ meV\AA{}, among the highest reported values in III-V materials.