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 $\sqrt{\ln \left(t\right)}$ dependence of the local slope, where $t$ is the growth time, and also by the roughness exponent $\alpha \simeq 0.9$ and interface growth exponent $\beta \simeq 0.26$. These characteristics clearly indicate that the growth is consistent with a statistical model of linear diffusion dynamics.