An STM study of current-induced step bunching on Si(111)

Abstract

We report quantitative measurement of terrace size as a function of annealing time for step bunching induced by direct current heating in the step-down direction for the temperatures 945°C and 1245°C. This result is shown to be inconsistent with simple models of step bunching in which there is a temperature-independent electromigration force on diffusing surface atoms. Deposition of Si atoms onto the surface held at 945°C with current running in the step-down direction slows the step bunching. By estimating the parameters governing step flow from experimental observations, this result is shown to be inconsistent with simple models of step bunching incorporating an electromigration force as the source of diffusional anisotropy. The evolution of step bunching was monitored by measuring the growth of the terrace sizes revealing a functional form of tα, with α∼0.5.