Electrical breakdown of a dielectric for the formation of a superconducting nanocontact

Abstract

Electrical breakdown of the dielectric nanolayer between film electrodes of niobium and an alloy of 50% indium and 50% tin forms a bridge of this alloy between the electrodes. The bridge resistance depends on the breakdown current. The length of the bridge is equal to the thickness of the dielectric (30 nm), and its diameter is 25 nm. The calculated coherence length of the alloy at 2 K is close to the length of the bridge. The calculated critical current of a bridge with a resistance of 1 Ω at a temperature of 0 K is 1 mA. It is concluded that such a bridge should have the properties of a Josephson contact at a temperature lower than the critical temperature of the alloy (6.5 K).