Conductance distribution in granular metal films: a combined study by conducting atomic force microscopy and computer simulation

We have studied the shape of the distribution F(G) for the conductance G between points on the surface of a metal–insulator nanocomposite film and the conducting substrate by Conducting Atomic Force Microscopy and computer simulation. Random resistor networks with both metallic and tunneling bonds included are used to model the nanocomposite films. The shape of F(G) is determined mainly by the connectivity of metal particles and the maximum tunneling distance in the composite. By qualitatively comparing the simulation results with the experimental data on granular NiFe-SiO2 films near the metal–insulator transition, we find important implications for the understanding of microscopic conduction mechanisms near the metal–insulator transition.