Anomalous dynamic scaling on the ion-sputtered Si(111) surface

The time evolution of an ion-sputtered Si(111) surface was investigated between 300 and 650 °C using the high-resolution low-energy electron diffraction technique. Below 450 °C, a (1×1) rough phase shows an anomalous dynamic-scaling behavior on the short-range scale where the measured height-height correlation has a form of ∼ln(t)${\mathit{r}}^{2\mathrm{\alpha }}$, which grows in time with a roughness exponent α=1.15±0.08. Such a behavior is consistent with the prediction by a recent dynamic-scaling theory. Above 530 °C, we found that the (7×7) phase does not undergo roughening evolution. The dramatic morphology change with temperature indicates a dynamic phase transition.