Scanning tunnelling microscopic images of annealed Ge(111) revealed large c(2 x 8) domains, with protrusions which closely matched the arrangement of adatom and rest-atom dangling bonds in the simple adatom model. The unit cell appeared asymmetrical or buckled; that is the 2 adatoms or the 2 rest atoms within the unit cell exhibited significant differences in apparent height. Both the adatom and rest-atom dangling bonds could be simultaneously observed with either bias polarity; indicating that both were partially filled.

Charge Transfer and Asymmetry on Ge(111)-c(2 x 8) Studied by Scanning Tunneling Microscopy. E.S.Hirschorn, D.S.Lin, F.M.Leibsle, A.Samsavar, T.C.Chiang: Physical Review B, 1991, 44, 1403-6