Anomalous coarsening process of voids, steps, and denuded zones on a Si(111)7x7 surface

Annealing a silicon surface covered with a submonolayer of a-Si at 600 degr ees C gives a surface with voids that undergo a ripening process. If the un covered surface has steps, the deposition of the growing and diffusing void s at this high temperature on the step creates a coarsening of the step. Th e coalescence of the voids with the step creates a denuded zone (in which t he density of voids is below the average) bath at the upper and the lower t erraces. It is shown here that both the exact morphology and the scaling of the step width on one hand, and the density of voids near the step on the other hand, can be analyzed quantitatively, The scaling relations of the st ep width, the dynamic scaling of the voids, the denuded zones, and the scal ing of the diffusion constant with size are shown to be interconnected Usin g all these relations, it is possible to get a complete picture of all the characteristics of this anomalous diffusive coarsening phenomenon. So we pr ove that the void coarsening process is dominated by void diffusion and coa lescence and that void diffusion is dominated by boundary vacancy diffusion . Thus the diffusive models of coarsening (described in the mean field by L ifshitz-Slyozov [I. M. Lifshitz and V. V. Slyozov, J. Phys. Chem. Solids 19 , 35 (1961); C. Wagnor, Z. Elektrochem. 65, 581 (1961)]) are nonrelevant in this case. [S1063-651X(99)02503-9].