The (110) GaAs surface of a structure containing ortho twins was studied using cross-sectional scanning tunnelling microscopy and the experimental results were compared with ab initio density functional theory calculations and STM simulations. It was found, both experimentally and theoretically, that the surface of various twin crystallites were significantly displaced with respect to each other, parallel to the twin boundary. This was explained by surface relaxation of the atoms in the (110) GaAs surface and the difference between the atomic configuration of the ortho twins.

Direct Observation of Atomic Scale Surface Relaxation in Ortho Twin Structures in GaAs by XSTM. J.Bolinsson, L.Ouattara, W.A.Hofer, N.Sköld, E.Lundgren, A.Gustafsson, A.Mikkelsen: Journal of Physics - Condensed Matter, 2009, 21[5], 055404