Percolative growth of palladium ultrathin films deposited by plasma sputtering

Palladium ultrathin films have been deposited by a plasma sputtering technique. In a first step, small particles (mean diameter d<3 nm), homogeneously distributed on amorphous carbon membrane surfaces. are grown by surface diffusion of Pd atoms. Coalescence starts to form meandering compound clusters. Such Pd clusters, composing the islands, are still enlarging during the deposition. During the coalescence, a percolating network builds up with a measured percolation threshold around p(c)=0.7. The time evolutions of the mean size of the elementary and compound clusters are slightly modified when compared to vacuum deposition and theoretical predictions. (C) 1998 Elsevier Science B.V. All rights reserved.