Preparation of a Superconducting Thin Film in a Chamber Cooled with Liquid N₂

Abstract

Superconducting thin films (Nb₃Ge, Nb₃Si and Nb) have been prepared in a chamber cooled with liquid N₂ at high rate by a magnetron sputtering method.
Following results were obtained.
(a) The chamber wall acts as a cryo-pump, trapping impurity gas during sputtering so that bell jar was completely separated from a pumping system to obtain environment free from oil. Nb films of three nine were obtained.
(b) Just after a deposition, thermal quenching down to 80 K was performed by a thermal conduction of sample holder which contact with liquid N₂ container. This method was tried for the first time. It was effective to depress an undersirous stable phase for preparing metastable Nb₃Ge and Nb₃Si. As a result, production of Nb₃Ge become easy and Nb₃Si was obtained with high TC nearly as high as by the explosion method.