Island-to-percolation transition during the room-temperature growth of sputtered nanoscale Pd films on hexagonal SiC

Abstract

We have studied the growth of room-temperature sputtered Pd films on 6H-SiC by using the atomic force microscopy technique. In particular, we analyzed the Pd film surface morphology as a function of the film thickness from 3 to 72 nm observing that the Pd grows initially (thickness 2-12 nm) as three-dimensional (3D) islands. Then (thickness 12-36 nm) the Pd film morphology evolves from compact 3D islands to partially coalesced wormlike structures, followed (36-60 nm) by a percolation morphology and finally to a continuous and rough film (at 72 nm). The application of the interrupted coalescence model allowed us to evaluate the critical mean islands diameter Rc ≈6.6 nm for the partial coalescence process while the application of the kinetic freezing model allowed us to evaluate the room-temperature Pd surface diffusion coefficient Ds ≈1.4× 10-17 m2 /s on 6H-SiC. Finally, the application of the Vincent's model allowed us to evaluate the critical Pd coverage Pc =68% for the percolation transition. © 2010 American Institute of Physics.