Step bunching to step-meandering transition induced by electromigration on Si(1 1 1) vicinal surface

The step configuration of a vicinal Si surface is studied under electromigration and a gradient of temperature. An abrupt transition (ΔT = 4 °C) from step-meandering to step bunching is found at 1225 °C for a step-down direct-current direction. This transition starts by random fluctuations which then extend on the whole surface. The transition is studied in the framework of a linear stability analysis of the usual Burton-Cabrera-Frank model by comparing the amplification factors of step-meandering and step bunching instabilities. Both compete at a given temperature, but since the amplification factors behave differently with temperature, bunching abruptly supersedes meandering above a critical temperature.