Effect of dissolved hydrogen on electrical properties of low-temperature tin films

A study was made to determine the effect of dissolved hydrogen on the electrical and superconducting properties of tin films deposited on a substrate cooled by liquid helium, with hydrogen at pressures of (1--9) x 10-5 torr present in the ambient vacuum. It has been found that dissolved hydrogen does strongly affect the electrical and superconducting properties of tin films, namely it causes an appreciable increase of their electrical resistance (by 1--2 orders of magnitude) and superconducting transition temperature T/sub c/ (by approximately 1 0K). The effect of hydrogen increases with its concentration and with decreasing thickness of the films. Furthermore, the R(T) curve of irreversible changes was found to have a minimum at about 25 0K evidently associated with an escape of dissolved hydrogen from the films. These results are discussed here on the basis of known theoretical concepts