The dynamics of atomic steps, and the interactions between them, were monitored via in situ scanning electron microscopy during the sublimation of a (111) surface which was atomically flat on a large scale (100μ x 50μ). Newly-nucleated widely-spaced steps moved at a constant velocity. In the case of more narrowly spaced steps, diffusion-mediated step-step interactions reduced the step velocity. In order to probe these interactions further, steps were made to collide. It was found that, in destructive collisions, the steps decelerated and flattened while, in constructive collisions, double atomic steps were produced.

Dynamics, interactions and collisions of atomic steps on Si(111) in sublimation P.Finnie, Y.Homma: Physical Review Letters, 1999, 82[13], 2737-40