Scanning Tunneling Microscopy of Anisotropic Monatomic Steps on a Vicinal Si(001)-2×1 Surface

Abstract
Using scanning tunneling microscopy (STM), we investigated the surface step structure of Si(001) with a misorientation of 0.3° towards [110]. The STM images show uniform (2×1)+(1×2) terraces (double domain structure) separated by monatomic height steps. Alternate terraces show straight and kinked step edges. This anisotropic feature of step edges is attributed to both a large difference in formation energy between the two types of steps and an anisotropic diffusion of surface adatoms.