Growth front roughening of room-temperature deposited copper nanocluster films

Growth front aspects of copper nanocluster films deposited with low energy onto silicon substrates at room temperature are investigated by atomic force microscopy. Analyses of the height-difference correlation function yield a roughness exponent H of 0.45+/-0.05. The root-mean-sqaure roughness amplitude w evolves with deposition time as a power law, wproportional tot(beta) (beta=0.62+/-0.07), leading also to a power-law increase of the local surface slope rho, rhoproportional tot(c) (c=0.73+/-0.09). These scaling exponents, in combination with an asymmetrical height distribution, point at a complex nonlinear roughening mechanism dominated by the formation of voids resulting in a highly porous film. (C) 2002 American Institute of Physics.