Si(1 1 1) step fluctuations in reflection electron microscopy at 1100 °C: anomalous step–step repulsion

Using reflection electron microscopy (REM) we study step fluctuations of Si(1 1 1) at 1100 °C. Sublimation is compensated by flux from a nearby crystal. The fluctuation behavior is qualitatively like that at 900 °C (where evaporation is negligible), with unexplained quantitative differences. Regarding the three parameters of the step continuum model of vicinal surfaces, the step stiffness is about half that at 900 °C, in agreement with theory. Step repulsions are at least six times as strong as predicted from 900 °C, suggesting non-equilibrium effects probably due to electromigration from the heating current. Temporal correlations have a large initial offset (due to slow scanning relative to fluctuations) but show scaling behavior.