Atomic resolution scanning tunnelling microscopic images of the (2 x 4) reconstruction, were presented which show the existence of at least four distinct surface structures. Two of these correspond to the α and β phases previously modelled from reflection high-energy electron diffraction experiments. The second layer structure within the missing row of the α-(2 x 4) phase was clearly resolved in these images Evidence was presented of dimer twist as part of the surface energy minimisation process of one of the α phases. Images of a previously unreported structure that exhibited (2 x 4) symmetry were shown.

Surface Atomic Structure of the GaAs(001)(2 x 4) Reconstruction. L.Broekman, R.Leckey, J.Riley, B.Usher, B.Sexton: Surface Science, 1995, 331-333[2], 1115-21