Length-scale dependence of the step bunch self-organization on patterned vicinal Si(111) surfaces - art. no. 071914

We use lithographic patterning and high-temperature annealing to investigate the length-scale dependence of self-organization of step bunches on vicinal Si(111) surfaces due to the motion and interference of misorientation-derived straight steps and the circular steps which bound cylindrical pits. Annealing of patterns with small pit diameters produces a rapid relaxation to straight step bunches, while larger structures maintain significant in-plane corrugations for as long as the out-of-plane corrugations persist. This indicates the existence of a characteristic length scale, set by the competition between the Gibbs-Thomson effect and sublimation. Significantly, the eventual relaxation is to nearly uniform step trains indicating that the late stage evolution is dominated by repulsive step-step interactions.