The formation of a 2 x 1 reconstruction upon ultra-thin (less than 4.5nm) strained layers which had been epitaxially grown on Si(111) was studied. Scanning tunnelling microscopy and reflection high-energy electron diffraction methods showed that the stable low-temperature (less than 450K) structure of the Si-rich surface consisted of chains which lay perpendicular to the three [2¯1¯1]-type directions. A structural model for the atomic rearrangement of this surface was presented, and agreed with the results of a detailed analysis of high-resolution scanning tunnelling microscope topographs.

R.Stalder, H.Sirringhaus, N.Onda, H.Von Känel: Surface Science, 1991, 258[1-3], 153-65