/Vs in shallow InAs quantum wells*

The two-dimensional electron gas (2DEG) formed in shallow InAs quantum wells with InGaAs barriers grown on InP is a promising platform for achieving topological superconductivity. Strong spin-orbit coupling and induced superconductivity are key ingredients. In addition, it is desirable to optimize 2DEG mobility. In this study, we assess the impact of modulation doping on shallow InAs quantum well heterostructures; we report on the magnetotransport properties as a function of the doping density and the spacer thickness. We find mobility may be enhanced in the modulation-doped heterostructures in which the silicon dopants are placed below the quantum well. Our analysis suggests that the doping layer pulls the electron wavefunction away from the surface, reducing the effect of surface scattering, leading to higher mobility. Impact on Rashba spin-orbit coupling and induced superconductivity will also be discussed.