Morphology of the rutile (110) surface after low sputter dose and annealing

The kinetics of diffusion-mediated smoothing of a TiO2 rutile (110) surface is studied over atomic length scales, by using a spot profile analysis of low-energy electron-diffraction data to characterize the morphology of the surface during thermal annealing. After the random removal of less than 1 ML of atoms by sputtering with an argon ion beam, the interface width and the distribution of terrace heights were found to stay nearly constant during annealing at 800 K, with terraces at just two heights making up ≅90% of the surface area over lateral distances of ≅400 A. Meanwhile, the coarsening of this nearly two-dimensional island structure is characterized by the growth of the average terrace width l from 20 to 60 A with annealing time, following l∼tβ with exponent β=0.24±0.04. In addition, the stability of an 8% occupation of a third terrace height indicates negligible diffusion flux between layers during annealing. These results are compared with existing models for the microscopic dynamics involved