The development of periodic atomic step arrays, associated with etched grating structures on Si(001) during annealing, was monitored by using optical and scanning tunnelling microscopic methods. It was found that the grating amplitudes decayed exponentially with time at temperatures ranging from 800 to 1100C; with characteristic decay constants that scaled approximately as the inverse fourth power of the grating period. This indicated the predominance of surface diffusion as the mass transport mechanism. The activation energy for Si surface self-diffusion was about 2.3eV, and the pre-exponential factor was about 0.1m2/s. The experimental data were consistent with an adatom transfer process. The details of the atomic step morphologies of the grating structures were described, and interactions of the atomic steps during decay were related to curvature-dependent driving forces for mass transfer.

Surface Self-Diffusion on Si from the Evolution of Periodic Atomic Step Arrays. M.E.Keeffe, C.C.Umbach, J.M.Blakely: Journal of the Physics and Chemistry of Solids, 1994, 55[10], 965-73