Potential disorder in granular metal systems: the field effect in discontinuous metal films

Abstract

The authors show that the conventional model for the basic physics of conduction in granular metals is unable to account for low-temperature field-effect measurements on discontinuous metal films. They discuss the physics of electrical contact between metals and insulators and show that it results in potential disorder that is large in comparison with other relevant energies. They explore the idea of electrostatic relaxation in the insulator and show that it correctly accounts for the small field effect that is observed and for its dependence on temperature and the activation energy for conduction. They have verified the role of electrostatic relaxation by direct experiments in which the relaxation processes are modified with the predicted consequences. They assert that potential disorder must play a dominant role as regards electrical transport in all granular systems.