High-functional Superconducting Tunnel Junction fabricated by Electron Beam Excited Plasma Ion Plating Method

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It is important to raise the tunneling efficiency of quasiparticles generated by incident X-ray or photon for the operation of superconducting tunneling junction as the detector. Using the electron beam evaporation technique under the high-vacuum pressure of 4 x 10^<-9>Pa, we fabricate epitaxial Nb and Ta layers on a sapphire substrate at the substrate temperature of 500 〜 700℃. Nb layer indicates the transition temperature (Tc) of 〜 9.3 K and the residual resistance ratio (RRR) of 〜 50. Ta layers indicates Tc 〜 4.5 K and RRR of 45 〜 140.We have fabricated a Nb/AlOx-Al/Nb Josephson junction using magnetron-facing target sputtering technique. Nb and Al layers can be deposited under the high-density plasma in the condition that it is not directly exposed to the plasma region generated between a pair of targets. The transition temperature of the Nb layer and the residual resistance ratio have indicated 9.3 K and more than 3. The Nb/AlOx-Al/Nb Josephson junction has exhibited current-voltage characteristics with a low subgap leakage current.