Field Effect Experiments on Discontinuous Metal Films

Abstract

ABSTRACTWe describe experiments in which the energetics of electrical conduction in discontinuous metal films are probed by inducing carriers electrostatically into the films. Both conductivity and thermopower show field effects that are generally of the expected form but they are very much smaller than the classic model for conduction in these systems would predict. Furthermore, in some cases at least, they can be shown to result from dielectric relaxation processes rather than from direct modification of basic transport energetics.We discuss possible explanations, including that large potential disorder is present and that transport is controlled by energy structure that moves with the chemical potential, as would be the case i correlation energies determined carrier mobility. Experiments that measure the charging energies of the metal particles directly suggest that correlation is important, and we argue that progress in understanding conduction in granular metals depends on development of a model in which correlation energies play a critical role in controlling transport.