Structure and stability of the Si(1 0 5) surface

Abstract Recent experimental studies have shown that well-annealed, unstrained Si(1 0 5) surfaces appear disordered and atomically rough when imaged using scanning tunnelling microscopy. We construct new models for the Si(1 0 5) surface that are based on single- and double-height steps separated by Si(0 0 1) terraces, and propose that the observed surface disorder of Si(1 0 5) originates from the presence of several structural models with different atomic-scale features but similar energies. This degeneracy can be removed by applying compressive strains, a result that is consistent with recent observations of the structure of the Ge/Si(1 0 5) surface.