Atomic force microscopy study of the growth mechanisms of nanostructured sputtered Au film on Si(111): Evolution with film thickness and annealing time

Nanostructured Au films were deposited on Si111 by room-temperature sputtering. By the atomic force microscopy technique we studied the evolution of the Au film morphology as a function of the film thickness h and annealing time t at 873 K. By the study of the evolution of the mean vertical and horizontal sizes of the islands forming the film and of their fraction of covered area as a function of h from 1.71017 to 1.01018 Au/cm2 we identified four different growth stages such as: 1 1.71017h3.01017 Au/cm2, nucleation of nanometric three-dimensional 3D hemispherical Au clusters; 2 3.01017h5.21017 Au/cm2, lateral growth of the Au clusters; 3 5.21017h7.71017 Au/cm2, coalescence of the Au clusters; 4 7.71017h1.0 1018 Au/cm2, vertical growth of the coalesced Au clusters. The application of the dynamic scaling theory of growing interfaces allowed us to calculate the dynamic scaling exponent z =3.80.3, the dynamic growth exponent =0.380.03, the roughness exponent =1.40.1 and the Avrami exponent m=0.790.02. Finally, the study of the evolution of the mean Au clusters size as a function of annealing time at 873 K allowed us to identify the thermal-induced self-organization mechanism in a surface diffusion limited ripening of 3D structures and also the surface diffusion coefficient of Au on Si111 at 873 K was estimated in 8.210−16310−17 m2 / s.