The evolution of conductivity in granular metal films, as a function of thickness and temperature, has been modeled by percolation within the framework of the theory of stochastic transport in disordered systems. The model was analytically worked out by means of the effective-medium approximation. The analytical expression obtained spans the entire range of resistance, from insulating to globally superconducting behavior, with increasing thickness. Quasireentrant or local superconductivity was found in our results as a consequence of tunneling junctions allowed in the model. Experimental data on tin films are considered.

• Received 12 March 1996

DOI:https://doi.org/10.1103/PhysRevB.55.3841