Morphological evolution of thin gold films studied by Auger electron spectroscopy in beading conditions

The evolution of thin gold films deposited on a sapphire surface was studied in UHV using Auger electron spectroscopy and atomic force microscopy techniques. The annealing temperatures were in the range 573-843 K. Starting from a continuous film, we observed at the end of the process a collection of beads. The incubation time in this temperature range was negligible, while the agglomeration time varied from about 2 h at 573 K to a few minutes at 843 K. The kinetics of metal agglomeration allowed the evaluation of the surface self diffusion coefficients of gold which can be expressed by D-s(m(2)/s)(573-843 K)= 3x10(-11)exp[-62+/-8(kJ/mol)/RT] . These results are in reasonable agreement with other published data. This method provides a framework for the evaluation of surface diffusion parameters of other metals.