RELATION BETWEEN MORPHOLOGY AND ALTERNATING-CURRENT ELECTRICAL-PROPERTIES OF GRANULAR METALLIC-FILMS CLOSE TO PERCOLATION-THRESHOLD

The purpose of this paper is to show how the low frequency electrical and dielectric properties may be related to the morphology of metallic thin films. To achieve this goal, we first summarize a recent compara tive morphological study of granular gold films deposited on amorphous and polycrystalline substrates. Then we present unpublished measureme nt of the frequency-dependent conductivity of the same thin films samp les in the range 10(2)-10(6) Hz in the immediate vicinity of the perco lation. These measurements indicate that the dispersion of the conduct ivity does not obey the classical percolation scaling laws. Taking adv antage of our morphological study of these films, we show that it is p ossible to discuss the nonuniversality of the frequency variation of t he electrical conductivity observed in these films in the framework of a new tunneling scaling law which depends on a morphology related tun neling factor and new scaling exponents.