STUDIES OF ALL-NIOBIUM ELECTRODE JOSEPHSON TUNNEL JUNCTIONS WITH AMORPHOPUS SILICON BARRIERS

This paper reports the fabrication and properties of small Nb--( a-Si )-Nb-(a-Si)-Nb Josephson tunnel junctions. The smallest junction area is about 0.3μm². A thin a-Si film deposited by electron beam evaporation was oxidized and used for the tunnel barriers. TEM and XPS investigations indicate that the barrier layers consist of SiO_x and Si. The junctions have been used for RF SQUID with an energy resolution of 1.9 x l0^-28 J/Hz.