Conductivity onset and superconducting properties of quench-condensed gallium films deposited onto different substrates

It is shown that the conductivity onset in cold deposited Ga films on glass substrates corresponds to the film thickness of 60-70 Angstrom in contrast to films deposited onto predeposited layers of SiO, where the conductivity onset can be observed at 10 times smaller thicknesses. A detailed investigation of superconducting properties of the films is also presented. We believe that chemical bonds between atoms are very important for the formation of the film structure, which can explain experimental results.