High-Quality Planar high-Tc Josephson Junctions

TL;DR

This paper presents a simple, reproducible ion irradiation method to create high-quality planar high-Tc Josephson junctions with tunable properties, enabling complex circuit fabrication.

Contribution

A novel two-step ion irradiation process for fabricating high-quality, reproducible high-Tc Josephson junctions with fine control over their characteristics.

Findings

Reproducible Josephson junctions with nearly ideal characteristics.

Process allows for fine tuning of junction properties.

Potential for complex circuit integration.

Abstract

Reproducible high-Tc Josephson junctions have been made in a rather simple two-step process using ion irradiation. A microbridge (1 to 5 ?m wide) is firstly designed by ion irradiating a c-axis-oriented YBa2Cu3O7-? film through a gold mask such as the non-protected part becomes insulating. A lower Tc part is then defined within the bridge by irradiating with a much lower fluence through a narrow slit (20 nm) opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. This process can be used to produce complex Josephson circuits.