Si(111) step fluctuations at high temperature: Anomalous step-step repulsion

Abstract

Using reflection electron microscopy we examine the step fluctuations of Si(111) at 1100°C. Evaporation is compensated by a replenishing flux. The step fluctuation behavior is qualitatively similar to that at 900°C (where sublimation is negligible), with unexplained quantitative differences. We focus on the three parameters of the step continuum model of vicinals. The step stiffness scales with an increase in T from 900°C as predicted by an appropriate lattice model. The kinetic coefficient is larger than scaling of the parameters from 900°C would predict. The step-step correlations are assessed in traditional and novel ways; step repulsions are at least 6 times as strong as predicted from lower temperatures, suggesting nonequilibrium effects probably due to electromigration.