Reconstructed (12,2,7) Si surface structure observed by scanning tunnelingmicroscopy

A series of reconstructed high-index Si surfaces, with angle beta from the [111] to [1 (1) over bar 0] direction varying between 10 degrees and 35 deg rees (in increments of 5 degrees) were systematically studied by ultrahigh vacuum scanning tunneling microscopy. The reconstruction of the (12, 2, 7) surface with beta=30 degrees as a typical example of the series was describ ed in detail. Fourier transforms revealed a (2x2) structure of the terrace, the splitting lattice on the step wall, and diffuse streaks from the kinks . The results were compared with other high-index surfaces of the beta seri es. The reconstructed terrace structures were separated into two groups by the boundary between beta=20 degrees and 25 degrees. With regard to the rec onstructed step wall structures, a remarkable characteristic pattern of the se high-index surfaces was clarified, namely that they are composed of seve ral splitting lattices. The degree of splitting proved to be closely propor tional to the effective dangling bond density. The diffuse streaks from the kinks were also observed as a common phenomenon of this series. (C) 2000 A merican Institute of Physics. [S0021-8979(00)01702-3].