The electronic properties of monolayer steps on (2 x 4)/c(2 x 8) reconstructed (001) surfaces were determined by means of ultra-high vacuum scanning tunnelling microscopy. Unit structures were proposed for the steps, and it was demonstrated that steps played the part of acceptor arrays. Electron-counting arguments concerning the steps explained the densities of kinks in As dimer rows on vicinal surfaces. It was found that the acceptors at the steps were identical to those at the kinks. It was confirmed that the surface states which were related to surface Fermi-level pinning were located at break points of a coherent arrangement of semiconducting (2 x 4) unit cells.

K.Kanisawa, H.Yamaguchi, Y.Horikoshi: Physical Review B, 1996, 54[7], 4428-31