The coarsening kinetics of the stepped-and-terrace groove structure formed on a vicinal Si(111) surface was investigated by in-situ synchrotron x-ray scattering. The time evolution of the groove period $L$ at various temperatures below the $(1\times 1)$-to-$(7\times 7)$ transition falls onto a universal curve when the annealing time is scaled by a scale factor. Distinctive stages of spinodal decomposition, coarsening, and saturation are identified in the evolution of the groove period. $L$ increases following a power law, $L\sim t^n$ with $n=1/6$ and 0.29 in the initial stage and the late stage of coarsening, respectively. The initial coarsening proceeds via collective motion of step bunches while the late stage is dominated by the diffusion of individual steps.

• Received 17 November 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.156103