An unusual defect structure which occurred on the (001) surface was studied by means of scanning tunnelling microscopy. The structure had c(8 x 8) periodicity, as revealed by both scanning tunnelling microscopic and low-energy electron diffraction data. Although Auger electron spectroscopy revealed an absence of contamination, secondary ion mass spectroscopy indicated the presence of trace amounts of Cu. This impurity was involved in the reconstruction, and was related to a similar mechanism for Ni-induced defect structures that had previously been found on Si(001). The c(8 x 8) structure was seen to consist of rows of raised rectangular structures that were formed by dimers that were added perpendicular to dimer rows on the terrace; with alternating rows out of phase.

P.W.Murray, R.Lindsay, F.M.Leibsle, P.L.Wincott, G.Thornton: Physical Review B, 1996, 54[19], 13468-71