Near-surface InAs two-dimensional electron gas on a GaAs substrate: Characterization and superconducting proximity effect

We have studied a near-surface, two-dimensional electron gas based on an InAs quantum well on a GaAs substrate. In devices without a dielectric layer, we estimated large electron mobilities on the order of 105 cm2/V. We have observed quantized conductance in a quantum point contact and determined the g factor. Using samples with an epitaxial Al layer, we defined multiple Josephson junctions and found the critical current to be gate-tunable. Based on multiple Andreev reflections, the semiconductor-superconductor interface is transparent, with an induced gap of 125 μeV. Our results suggest that this InAs system is a viable platform for use in hybrid topological superconductor devices.