Near-surface InAs 2DEG on a GaAs substrate: characterization and superconducting proximity effect

TL;DR

This study characterizes a near-surface InAs 2DEG on GaAs, demonstrating high mobility, quantized conductance, and gate-tunable Josephson junctions, highlighting its potential for hybrid topological superconductor applications.

Contribution

It provides a comprehensive characterization of InAs 2DEG on GaAs with superconducting contacts, showing high mobility, quantized conductance, and transparent interfaces for topological device prospects.

Findings

Electron mobility around 10^5 cm^2/Vs

Quantized conductance observed in quantum point contact

Gate-tunable critical current in Josephson junctions

Abstract

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 $10^5$ cm$^2$/Vs. 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 ${\mu}$eV. Our results demonstrate the viability of this platform for hybrid topological superconductor devices.