Electrical Properties of Selective-Area-Grown Superconductor-Semiconductor Hybrid Structures on Silicon

TL;DR

This paper demonstrates a scalable superconductor-semiconductor hybrid system on silicon with high mobility and superconducting properties, enabling advanced quantum devices.

Contribution

It introduces a monolithic, selective-area growth method for superconductor-semiconductor structures directly on silicon, with detailed electrical characterization.

Findings

High InAs mobility of approximately 3200 cm²/Vs.

Observation of a hard superconducting gap and high interface transmission.

Gate-tunable Josephson junctions with significant critical current and multiple Andreev reflections.

Abstract

We present a superconductor-semiconductor material system that is both scalable and monolithically integrated on a silicon substrate. It uses selective area growth of Al-InAs hybrid structures on a planar III-V buffer layer, grown directly on a high resistivity silicon substrate. We characterized the electrical properties of this material system at millikelvin temperatures and observed a high average field-effect mobility of $\mu \approx 3200\,\mathrm{cm^2/Vs}$ for the InAs channel, and a hard induced superconducting gap. Josephson junctions exhibited a high interface transmission, $\mathcal{T} \approx 0.75 $, gate voltage tunable switching current with a product of critical current and normal state resistance, $I_{\mathrm{C}}R_{\mathrm{N}} \approx 83\,\mathrm{\mu V}$, and signatures of multiple Andreev reflections. These results pave the way for scalable and high coherent gate voltage tunable transmon devices and other superconductor-semiconductor hybrids fabricated directly on silicon.