Interplay of stress, structure, and stoichiometry in Ge-covered Si(001)

By calculating the evolution of surface energies and surface stress tensors of Ge-covered Si(001) with increasing Ge coverage, we derive the most probable Ge stoichiometry in the subsurface regions beyond 1 monolayer coverage. We compare the calculated surface reconstruction and surface stress at the thermodynamic and kinetic limits to experiment to provide a quantitative understanding of the recently observed Ge-induced reversal of surface stress anisotropy.