STEP PERMEABILITY AND THE RELAXATION OF BIPERIODIC GRATINGS ON SI(001)

We have used low energy electron microscopy to study the time dependen ce of atomic height islands and holes at the extrema of a fabricated b iperiodic grating on Si(001), From the pairwise disappearance of these islands and holes as the grating thermally smooths we conclude that s teps on Si(001) are remarkably permeable, i.e., adatoms can cross step s without becoming incorporated into them. Comparison of the time depe ndence of the island areas with model calculations shows that the adat om incorporation probability is actually much smaller than the crossin g probability.