Wavy steps on Si(001)

Abstract

Using low-energy electron microscopy we have found a new phase transition on the Si(001) surface at miscut angles smaller than \ensuremath{\sim}0.1\ifmmode^\circ\else\textdegree\fi{}. The surface phase separates into facets with \ensuremath{\sim}300 \AA{} terrace width, and regions with much larger, wavy terraces. This wavy phase is stabilized by a reduction of surface-stress-induced strain energy. A theoretical study by Tersoff and Pehlke compares favorably with our observations.