Growth front aspects of copper nanocluster films deposited with low energy onto
silicon substrates at room temperature are investigated using atomic force
microscopy. Analyses of the height-difference correlation function yield a roughness
exponent H=0.4510.05. The rms roughness amplitude w evolves with deposition time as
a power law, [ ], with a growth exponent b=0.6210.07. These scaling exponents,
in combination with an asymmetrical height distribution, suggest a complex
non-linear roughening mechanism dominated by the formation of pores, resulting in a
low density film. X-ray scattering reflectivity measurements indicated pore sizes as
low as 5 nm.
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