Shubnikov-de Haas Characterization of Superconductor-Semiconductor Heterostructures

TL;DR

This paper introduces a simple method using Shubnikov-de Haas oscillations to characterize key material parameters in superconductor-semiconductor heterostructures, aiding optimization for quantum applications.

Contribution

The authors develop a new approach to extract carrier density, spin-orbit coupling, and scattering times from magnetoresistance data in hybrid structures.

Findings

Extracted scattering times reveal metal-semiconductor coupling strength.

Method allows estimation of proximity-induced superconducting gap.

Characterization achieved without complex fabrication or ultra-low temperature measurements.

Abstract

Hybrid superconductor-semiconductor nanostructures are a central component for research spanning condensed matter physics and quantum information processing. Continued progress relies critically on the ability to characterize, control, and optimize several intrinsic material properties including spin-orbit coupling, band offsets, and disorder in a device-relevant stack that necessarily couples the electronic states of a superconducting metal film and a semiconductor. Here we report a new method to extract fundamental material parameters utilizing simple Shubnikov-de Haas (SdH) oscillation measurements in heterostructures in which metallic electronic states are coupled to a two-dimensional electron gas (2DEG) residing in an InAs quantum well beneath an aluminum thin film. Proper analysis of the full magnetoresistance data facilitates extraction of the quantum well carrier density, spin-orbit coupling strength, and both transport and quantum scattering times. Most importantly, the extracted scattering times in the 2DEG are impacted by the metal-semiconductor coupling strength allowing us to quickly gain information on proximity-induced superconducting gap without any fabrication or mK measurements. The wealth of information that is accessed with these simple measurements positions this methodology as an important tool for hybrid materials optimization.