Investigation of the two-dimensional electron gas in InSb1−xAsx quantum wells: a promising platform for topological superconductivity

Abstract

The two-dimensional electron gas (2DEG) confined in InSb₁−_xAs_x quantum wells is a promising platform for exploration of topological superconductivity in hybrid superconductor/semiconductor devices. InSb₁−_xAs_x presents itself as a superior material since it is predicted to have higher spin-orbit coupling (SOC) and effective g-factor compared to commonly used InAs and InSb. In this talk, I will show how our preliminary results suggest that InSb₁−_xAs_x 2DEGs are a promising avenue for topological superconductivity by reporting on enhanced SOC and electron scattering in our high-quality InSbAs quantum wells. We explored a series of 30 nm quantum wells with arsenic mole fraction of x = 0.05, 0.13 and 0.19. At x = 0.05 the 2DEG displays a mobility peak of 24 m²/Vs at a density of 2.5× 10¹⁵ m⁻², comparable to previously reported mobility in undoped InSb quantum wells of similar design. We also analyze the dependency of mobility with 2DEG density and arsenic mole fraction and extract an alloy scattering rate of _τalloy=45 ns⁻¹ per %As. High mobility, small effective mass, and strong SOC result in beating in the Shubnikov de Haas oscillations at low magnetic field, facilitating assessment of the Rashba coupling parameter. We observe a gate tunable zero-field spin splitting, which increases with higher arsenic mole fraction when samples are compared at fixed 2DEG density. The maximum Rashba parameter extracted is ∼ 30 meVnm for x = 0.19, among the highest values reported in III-V semiconductors in comparable structures. 

https://purdue-edu.zoom.us/j/96477307398 

Meeting ID: 964 7730 7398