Engineering the spin-orbit interaction in InAs-based quantum wells for superconductor-semiconductor hybrid structures*

Superconductor (SC)-semiconductor hybrid structures open an access to exotic superconductivity, enabling the creation of Majorana zero modes in appropriate devices. The strength of the spin-orbit interaction (SOI) in the structure represents an important parameter, driving for example the size of the energy gap induced into the SC. InAs-based epitaxial hybrid heterostructures have emerged as a promising candidate for such systems, exploiting the rather large intrinsic SOI of InAs and the epitaxial matching with SCs such as aluminum (Al).
In this work, we present a systematic study of two-dimensional electron gases (2DEGs) realized in strongly asymmetric InAs/InGaAs/InAlAs quantum well layouts. We show that the SOI in such 2DEGs is substantially enhanced by engineering the asymmetry through the position of the InAs inset and the doping layer. We characterize the strength of the SOI in the 2DEGs by analyzing SOI-induced features in low temperature magneto transport, such as zero-field spin splitting-induced beating patterns and weak antilocalization, as well as by exploring the energy gap induced into epitaxial superconducting Al.