Numerical study of conductance distribution in granular metal films

We study the shape of distribution F(G) for the conductance G between a point on the surface of a metal-insulator nanocomposite film and the conducting substrate. Random resistor networks with both metallic and tunneling bonds included are used to model nanocomposite films. Our simulation results show explicitly that the shape of F(G) is determined mainly by the connectivity of metal particles and the maximum tunneling distance in the composite. By applying our results to the available experimental data on granular NiFe-SiO₂, we find important implications for the understanding of microscopic conduction mechanisms near the metal-insulator transition.