Repairing the surface of InAs-based topological heterostructures

Candidate systems for topologically-protected qubits include two-dimensional electron gases (2DEGs) based on heterostructures exhibiting a strong spin–orbit interaction and superconductivity via the proximity effect. For InAs- or InSb-based materials, the need to form shallow quantum wells to create a hard-gapped p-wave superconducting state often subjects them to fabrication-induced damage, limiting their mobility. Here, we examine scattering mechanisms in processed InAs 2DEG quantum wells and demonstrate a means of increasing their mobility via repairing the semiconductor–dielectric interface. Passivation of charged impurity states with an argon–hydrogen plasma results in a significant increase in the measured mobility and reduction in its variance relative to untreated samples, up to 45 300 cm 2/(V s) in a 10 nm deep quantum well.