Conductivity and superconductive properties of granular Sn--Ge films

The conductivity mechanisms and superconductive properties of island tin condensates in a germanium matrix are studied. Applicability limits are determined for Mott's law, valid for systems with hopping conductivity between centers of charge carrier localization. It is shown that within one and the same specimen with fixed distribution of tin granules the transparency of the intergranule barriers may be controlled and the nature of the superconductive transition changed from a partial one, related to the superconductivity of the individual granules, to a complete one characteristic of particle systems with Josephson coupling, by crystallization of the amorphous germanium in the Sn--Ge system