Controlling the Intrinsic Josephson Junction Number in a $\mathbf{Bi_2Sr_2CaCu_2O_{8+\delta}}$ Mesa

TL;DR

This paper presents a modified fabrication process for intrinsic Josephson junctions in Bi-2212 mesas, enabling precise control over the number of junctions, including the creation of a single junction, by adjusting etching parameters.

Contribution

The study introduces a method to accurately control the number of intrinsic Josephson junctions in Bi-2212 mesas through reduced etching rates and process adjustments, improving fabrication precision.

Findings

Junction number control within ±1 accuracy.

Ability to produce a single Josephson junction.

Enhanced fabrication process for precise junction control.

Abstract

In fabricating $\mathrm{Bi_2Sr_2CaCu_2O_{8+\delta}}$ intrinsic Josephson junctions in 4-terminal mesa structures, we modify the conventional fabrication process by markedly reducing the etching rates of argon ion milling. As a result, the junction number in a stack can be controlled quite satisfactorily as long as we carefully adjust those factors such as the etching time and the thickness of the evaporated layers. The error in the junction number is within $\pm 1$. By additional ion etching if necessary, we can controllably decrease the junction number to a rather small value, and even a single intrinsic Josephson junction can be produced.