Properties of superconducting rf sputtered ultrathin films of Nb

Journal Article · Thu Jan 01 04:00:00 EST 1976 · Journal of Vacuum Science and Technology

DOI:https://doi.org/10.1116/1.568809· OSTI ID:4035987

Wolf, Stuart A.

Superconducting niobium films, both cylindrical and planar, have been prepared by rf sputtering in an uhv chamber which is routinely pumped to a residual pressure of 3x10$sup -9$ torr. The superconducting transition temperature T/subc/ of films with thicknesses greater than 2000 A was near 9.2$sup 0$K, the bulk value, while T/subc/ decreased linearly with inverse thickness for films thinner than 1000 A. Superconductivity was observed for the first time in Nb films thinner than 50 A; the T/subc/ of a 40 A film was 4.4$sup 0$K while for a 27 A film the onset of the transition was about 2$sup 0$K. Electrical continuity was maintained down to a nominal film thickness of less than 10 A, but this film was not superconducting above 1.5$sup 0$K. These results are compared with a model which predicts the dependence of T/subc/ on thickness. (AIP)

• Research Organization: Naval Research Laboratory, Washington, D.C. 20375
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-030169
• OSTI ID: 4035987
• Journal Information: Journal of Vacuum Science and Technology, Journal Name: Journal of Vacuum Science and Technology Journal Issue: 1 Vol. 13; ISSN 0022-5355
• Country of Publication: United States
• Language: English

Related Subjects

*NIOBIUM-- TRANSITION TEMPERATURE
360104* --Materials--Metals & Alloys--Physical Properties
FILMS
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
N66200 --Physics (Low Temperature)--Superconductivity
SPUTTERING
TEMPERATURE DEPENDENCE
THICKNESS
ULTRAHIGH VACUUM