Complete stabilization and improvement of the characteristics of tunnel junctions by thermal annealing

TL;DR

This study demonstrates that vacuum annealing of submicron Al-AlOx-Al tunnel junctions at high temperatures completely stabilizes their properties and enhances tunneling characteristics by eliminating resonances and increasing key parameters.

Contribution

The paper presents a method to fully stabilize and improve tunnel junctions through thermal annealing, a novel approach for enhancing device reliability.

Findings

Complete stabilization of junctions after annealing.

Increase in tunneling resistance, barrier thickness, and height.

Disappearance of unwanted resonances in tunneling characteristics.

Abstract

We have observed that submicron sized Al--AlO{$_x$}--Al tunnel junctions can be stabilized completely by annealing them in vacuum at temperatures between $350^{\circ}$C and $450^{\circ}$C. In addition, low temperature characterization of the samples after the annealing treatment showed a marked improvement of the tunneling characteristics due to disappearance of unwanted resonances in the current. Charging energy, tunneling resistance, barrier thickness and height all increase after the treatment. The superconducting gap is not affected, but supercurrent is reduced in accordance with the increase of tunneling resistance.