INFLUENCE OF CHARGE DISORDER IN NETWORKS OF SMALL TUNNEL-JUNCTIONS

We have investigated experimentally the transport properties of two-di mensional arrays of small tunnel junctions in the charging regime. In such arrays, the random offset charges caused by impurities in the und erlying substrate or in the tunnel barriers are expected to strongly a ffect the conduction. The current through the arrays oscillates period ically with the gate voltage and we have found a linear dependence of the Coulomb voltage gap with the length of the array. These results ar e a direct measurement of the influence of charge disorder on Coulomb blockade and are in good agreement with theoretical predictions.