Decay of surface charge between electrodes on insulator surfaces

We examine the rate at which surface charge sitting on the interface between two dielectrics leaks away to adjacent electrodes. We show that as the decay progresses, the charge density tends to assume a self-similar distribution. If the interface is conductive, then the decay of this asymptotic form takes place exponentially, whereas the decay is hyperbolic for a surface-charge-driven system, so we can deduce the mechanism from experimental measurements. The shapes of the two distributions are distinctive, allowing independent confirmation.