Jpn. J. Appl. Phys. 16 (1977) pp. 509-514  |Next Article|  |Table of Contents|
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Superconducting Transition Temperature of Nb–Ge Thin Films Prepared by Co-Evaporation

Yoshinobu Tarutani and Mitsuhiro Kudo

(Received September 17, 1976)

Nb–Ge thin films are prepared by co-evaporating Nb and Ge. Dependences of the superconducting critical temperature T_c the lattice parameter a_o and the resistivity on preparation conditions are studied. As the substrate temperature lowers from 1000 to 800°C, a_o remains constant but T_c is lowered. Lowering the deposition rate results in a decrease in a_o and an increase in T_c. T_c stays constant for the film thickness d larger than 2000 Å and is lowered for d smaller than 2000 Å. Especially, T_c is less than 4.2 K when d is smaller than 50 Å. The lattice parameter of the stoichiometric Nb₃Ge is estimated to be 5.12₇ Å by extrapolating the a_o's of single phase Nb–Ge thin films. A morphological study of Nb–Ge thin films is made by transmission electron microscopy. They consist of polycrystalline grains of about 500 Å in diameter.

URL: http://jjap.jsap.jp/link?JJAP/16/509/
DOI: 10.1143/JJAP.16.509

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