Instability of kinetic roughening in sputter-deposition growth of Pt on glass

Using scanning tunneling microscopy, we have studied the kinetic roughening in the growth of Pt sputter deposited on glass at room temperature for a film thickness range of 15-140 nm. The growth exhibits an irregularly growing mound morphology and shows an instability with anomalous scaling behavior characterized by the root ln(t) dependence of the local slope, where t is the growth time, and also by the roughness exponent alpha similar or equal to 0.9 and interface growth exponent beta similar or equal to 0.26. These characteristics clearly indicate that the growth is consistent with a statistical model of linear diffusion dynamics.