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Published online by Cambridge University Press: 10 February 2011
Topological disorder places constraints on the local flow of currents in granular thin films of metals and semiconductors. These constraints in turn influence measurable transport properties such as conductance and conductance fluctuations for these films. We quantify disorder in the disposition of grains within real and simulated thin films by applying methods originally developed studying foam evolution. For simulated Voronoi resistor networks the overall conductance of a film with a given grain density achieves a minimum value for an intermediate degree of disorder. Films of equal conductances on either side of this minimum can have strikingly different current distributions. Short range inhomogeneities in the size and placement of grains lead to large scale conductivity inhomogeneities in disordered films. This renders the disordered films more susceptible to 1/f noise for systems with nonlinear intergrain coupling due to factors such as hydrogen diffusion. We discuss the results of simulations of such systems in the context of transport and scanning probe microscopy measurements on a-Si:H thin films.