Superconducting proximity effect in inverted InAs/GaSb quantum well structures with Ta electrodes

TL;DR

This study investigates the superconducting proximity effect in InAs/GaSb quantum wells with Ta electrodes, revealing how interface transparency influences zero-bias conductance features and demonstrating the applicability of BTK theory.

Contribution

It provides experimental insights into how interface transparency affects superconducting proximity effects in InAs/GaSb quantum wells with Ta electrodes.

Findings

Resistive interfaces show a broad zero-bias conductance peak.

Transparent interfaces exhibit a zero-bias conductance dip with coherence peaks.

Conductance spectra fit well with Blonder-Tinkham-Klapwijk theory.

Abstract

We present our recent electronic transport results in top-gated InAs/GaSb quantum well hybrid structures with superconducting Ta electrodes. We show that the transport across the InAs-Ta junction depends largely on the interfacial transparency, exhibiting distinct zero-bias behavior. For a relatively resistive interface a broad conductance peak is observed at zero bias. When a transparent InAs-Ta interface is achieved, a zero-bias conductance dip appears with two coherent-peak-like features forming at bias voltages corresponding to the superconducting gap of Ta. The conductance spectra of the transparent InAs-Ta junction at different gate voltages can be fit well using the standard Blonder-Tinkham-Klapwijk theory.