Periodic arrays of large hexagonal tiles (up to 170Å in size) were observed on As/Ge(111) surfaces. First-principles total energy calculations combined with scanning tunnelling microscopy reveal a (5-7-5)-ringed structure for the trenches that separate the tiles. It was found that trenches formed via an exothermic process. The calculated equilibrium trench spacing of ∼104Å agreed with experiment. Comparison between first-principles calculations and continuum elasticity theory suggests that the observed mesoscopic reconstruction was driven entirely by long-range surface strain relaxation.

Strain-Driven Mesoscopic Reconstruction of the As/Ge(111) Surface. W.E.McMahon, I.G.Batyrev, J.M.Olson, S.B.Zhang: Physical Review Letters, 2002, 89[7], 076103 (4pp)