Fabrication of Nb3Ge/Si(SiOx)/Pb Josephson tunneling junction

The Josephson junction of Nb3Ge was fabricated by using a Si(SiOx) thin film as the tunnel barrier and Pb as a counter electrode. The thickness of the Si barrier is 2 nm, and the junction size is 0.5 × 0.5 mm2. The critical current of the junction was 8 ∼ 12 Acm-2. the normal-state tunneling resistance was30 ~ 60 μ 2. The onset voltage of gap was 5.2 mV. The Shapiro step mode and the Fiske step mode were observed in a well-defined shape. The dependence of maximum dc-Josephson current upon external magnetic field gives the penetration depth of Nb3Ge of 130 nm. The dependence of the resonance voltage upon external magnetic field gives the dielectric constant 8.7 of the Si(SiOx) barrier.