Strain-driven mesoscopic reconstruction of the As/Ge(111) surface.

Abstract

Periodic arrays of large hexagonal tiles (up to 170 A in size) are observed on As/Ge(111) surfaces. First-principles total energy calculations combined with scanning tunneling microscopy reveal a (5-7-5)-ringed structure for the trenches that separate the tiles. We find that trenches form via an exothermic process. The calculated equilibrium trench spacing of approximately 104 A agrees with experiment. Comparison between first-principles calculations and continuum elasticity theory suggests that the observed mesoscopic reconstruction is driven entirely by long-range surface strain relaxation.