Si(111)-α-√3x√3-Au phase modified by In adsorption:: Stabilization of a homogeneous surface by stress relief

Structural transformations on the Si(111)-alpha-root 3 x root 3-Au surface induced by In adsorption have been studied using scanning tunneling microscopy and first-principles total-energy calculations. It has been found that In adsorption results in the transformation of the root 3 x root 3-Au phase to the root 3 x root 3-(Au, In) phase. At room temperature, the transformation is limited by the interior of the original root 3 x root 3-Au domains and does not affect the domain-wall structure. Upon annealing at 600 S C, the domain walls are eliminated and highly ordered almost defect-free homogeneous root 3 x root 3-(Au, In) surface develops. The root 3 x root 3-(Au, In) surface phase contains 1 monolayer (ML) of Au, 1 ML of Si and about 0.15 ML of In. Plausible mechanism of stabilization of the domain-wall-free Si (111) root 3 x root 3-(Au, In) surface is the stress relief caused by In adsorption.