Single-electron tunneling in thin metal granular films

Electrical transport properties of extremely thin metal (Ag and Au) granular films fabricated by a cosputtering method were studied. High-resolution transmission electron microscopic observations revealed that Ag (Au) nanocrystals several nanometers in diameter were dispersed in thin films. In spite of the large size (100 x 100 mu m(2)) of the devices prepared, the Coulomb blockade and the Coulomb staircase were observed on current-voltage (I-V) characteristics at relatively high temperature (100 K). Although the samples were prepared under the same conditions, the I-V curves varied from sample to sample. The observed I-V curves were well fitted by Monte Carlo simulation assuming that the samples consist of a few serial and parallel connections of nanocrystals. The present results suggest that the macroscopic conduction of thin granular films is dominated by only a few special conduction paths. (C) 1999 Elsevier Science S.A. All rights reserved.