  Steps with spacings of microns form on top of mesas fabricated on Si(111)
that is annealed at temperatures where sublimation becomes important. Upon
annealing, mesas first develop ridges along their edges, effectively creating
craters which then become step-free by a step flow process described in the
literature. Due to the miscut of the average surface from (111), ridge
breakdown occurs on one edge of each mesa as sublimation proceeds. The
breakdown point then acts as a source of steps which spread out over the mesa
surface. The distribution of steps in the resulting step train depends on the
sublimation rate, direct step-step interaction and the diffusive exchange of
atoms among the steps. Computer simulations using BCF (Burton, Cabrera and
Frank) theory provide insight into the controlling processes. The results
suggest that self-organization of the wide terrace distributions in the low
step density area occurs under sublimation. We compare the experimental and
predicted step distributions.

Materials Science