Band structure probe of near Surface InAs Quantum Wells*

Near surface InAs quantum wells (QW) have recently attracted a great deal of interest as tools to explore mesoscopic and topological superconductivity. These shallow QWs can interact strongly with superconducting layers which can be epitaxially grown on their surfaces. In this talk, we present a combined experimental and theoretical approach to study the band structure of these QWs. The effective mass and g-factors in these QWs were determined using high field cyclotron resonance (CR). Unlike GaAs, narrow gap systems like InAs have large nonparabolicity in their band structures.The band parameters extracted from our CR experiments are consistent with those obtained from Shubnikov de Hass measurements and agree remarkably well with the theoretical calculations. Our band structure models include strong mixing of the conduction and valence bands which leads to a large non-parabolicity. The calculations accurately describe the experimental observations and allowing us to accurately map the effective mass and g-factor as a function of magnetic field, Landau level index, and the well width for different near surface InAs QWs.