The clean (001) 2 x 1 surface was studied by means of scanning tunnelling microscopy. Many different dimer-vacancy defects and complexes were seen at the surface. Complexes which consisted of a missing dimer, a twin missing-dimer, and an intermediate dimer (the 1 + 2 dimer-vacancy complex) made up the great majority of those detected. Line scans of the 1 + 2 dimer-vacancy complex strongly supported a structural model which had been proposed for the 1 + 2 dimer-vacancy complex on the Si(001) surface. Information on the interactions between neighboring dimers was also obtained, and differences between the Ge(001) and Si(001) surfaces were noted.

W.S.Yang, X.D.Wang, K.Cho, J.Kishimoto, S.Fukatsu, T.Hashizume, T.Sakurai: Physical Review B, 1994, 50[4], 2406-8