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

Abstract

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