エリプソメータを用いたジョセフソン接合酸化膜の形成過程の測定

抄録

Josephson tunneling junctions have been fabricated using the rf plasma oxidation method. Prior to the junction formation, the oxide growing processes on Pb or Pb-In alloy films have been investigated in detail with the aid of in situ ellipsometry. The oxide thickness tends to saturate under appropriate oxidation and sputtering parameters. The steady state oxide thickness has been in the 6070 Å range for Pb and in the 4050 Å range for Pb-In alloy (In 10 wt%). Referring these results, we have fabricated tunneling junctions whose base electrodes have been made of Pb-In/Au alloy film. The counter electrodes have been made of Pb-In alloy film or sequentially deposited Pb/ Au/Pb film. The junctions with Pb/Au/Pb counter electrodes have exhibited good I-V characteristics with little scattering of the normal tunneling resistance.