The surface stress anisotropy was determined by analyzing the equilibrium shape of vacancy islands on the Ge(001) surface. This anisotropy was the difference between the compressive stress component along the substrate dimer rows, and the tensile stress component perpendicular to the substrate dimer rows. In order to extract the surface stress anisotropy, a recently proposed model was used. The surface stress anisotropy of the clean Ge(001) surface was found to be 0.08eV/Å2. This value was comparable to the surface stress anisotropy of the closely-related Si(001) surface.

Surface Stress Anisotropy of Ge(001). M.T.Middel, H.J.W.Zandvliet, B.Poelsema: Physical Review Letters, 2002, 88[19], 196105 (4pp)