Low-temperature transport properties of granular Pb films below the percolation threshold

摘要: The author studies the transport properties of disconnected Pb films from 77 down to 0.05 K, at zero and high applied magnetic fields. conductivity between separated metal clusters is found be dominated by voltage injection not thermal excitation electrons low temperatures. This explains temperature-independent resistance tails in both superconductivity normal state films, observed temperatures this other experiments. I-V characteristics were follow a power law I varies as Vn, n>2, temperatures, consistent with space-charge-limited current model for conductivity.