Morphology-transitions at vicinal Cu-surfaces

An extension of the Burton-Cabrera-Frank model [Phil. Trans. R. Soc. London, Ser. A 243, 299 (1951)] including diffusion along steps and entropic step-step interaction is introduced. This extended model is successfully applied to simulate experiments done in the group of H.-J. Ernst at CEA Saclay, France, for vicinal Cu surfaces. In particular, the rise of two qualitatively different morphologies can be explained by the competition of growth directions implied by the four distinct driving and restoring forces of the model. Each of those forces sets a length scale for the dominant mode of a developing step instability. This explains that the wavelengthes of meandering-instabilities observed at vicinal surfaces experimentally are usually larger than the one predicted by Bales and Zangwill [Phys. Rev. B 41, 5500 (1990)] theoretically.