PNNL

Abstract

The analysis of the dynamics of equilibrium step fluctuations has been extended to a chemically heterogeneous surface. The multicomponent reconstructed Al/Si~111!-~)3)! surface has been studied using variabletemperature scanning tunneling microscopy at elevated temperatures. The temporal correlation functions for both single steps and step arrays follow a t1/2 dependence over the entire temperature range ~770–1020 K!, consistent with a rate limiting mechanism of random attachment and detachment of atoms at step edges. The alternative mechanism, diffusion from step-to-step, is shown to be inconsistent with more detailed analytic approximations to the correlation function for the measured step-step separation. An activation energy of 1.9 eV and the major kinetic parameters that govern surface mass transport and step equilibration processes have been determined.