High quality superconducting tunnel junction barriers using atomic layer deposition

TL;DR

This paper presents a novel atomic layer deposition technique to create high-quality, large-area superconducting tunnel junction barriers, enabling improved thermometry and potential applications in low-temperature refrigeration.

Contribution

It introduces a new fabrication method combining atomic layer deposition with an aluminum wetting layer for superior tunnel junction barriers.

Findings

Single-particle tunneling confirmed as dominant transport mechanism

Current-voltage curves show device viability as low-temperature thermometers

Potential for high-performance junction refrigerators

Abstract

We demonstrate a technique for creating high quality, large area tunnel junction barriers for normal-insulating- superconducting or superconducting-insulating-superconducting tunnel junctions. We use atomic layer depo- sition and an aluminum wetting layer to form a nanometer scale insulating barrier on gold films. Electronic transport measurements confirm that single-particle electron tunneling is the dominant transport mechanism, and the measured current-voltage curves demonstrate the viability of using these devices as self-calibrated, low temperature thermometers with a wide range of tunable parameters. The potential for fabricating high performance junction refrigerators is also highlighted.