Mass transport by surface diffusion on rough Ge(001) surfaces is characterized using in situ scanning tunneling microscopy. Rough starting surfaces with nearly constant step densities are prepared by low-energy ion etching at 270 °C; the characteristic in-plane length scale of the roughness is varied from 37 to 118 nm. These surfaces are subsequently annealed at 245-325 °C for times between 10 min and 6 h and imaged at room temperature. The activation energy for surface smoothing is 1.9 ± 0.25 eV. The dependence of the relaxation rate on the in-plane length scale is inconsistent with the continuum model of Mullins: the time constant τ of the smoothing process increases with increasing lateral length scale L as τ ∝ Ln, n = 2.2 ± 0.4.
ASJC Scopus subject areas
- Physics and Astronomy(all)