The reconstruction of (100) surfaces was directly imaged by using reflection electron microscopy and the minimum exposure technique. Domains which contained various superstructures coexisted on these surfaces, and exhibited certain orientation relationships. The existence of a (27-1 272) reconstruction with large unit cells was deduced from superlattice fringes which were observed to be highly sensitive to the observation direction in reflection electron microscopic images. These large unit cells were considered to be generated by a long-range modulation of the (27-2 25) reconstruction. A model which was based upon a compressed and twisted so-called Hex overlayer on a square substrate was suggested in order to explain the reconstruction which was observed on these surfaces.

N.Wang, Y.Uchida, G.Lehmpfuhl: Surface Science Letters, 1993, 284, L419-25