Growth instabilities and adsorbed impurities: A case study

A kinetic Monte-Carlo study of the meandering instability of a vicinal surface growing by step flow is performed. Impurities are codeposited during growth, and they are shown to be responsible for quantitative and qualitative modifications of the surface morphology. In particular, impurities make adatom diffusion less dependent on the deposition rate, affecting thus the wavelength of the meanders. Impurities also act as nucleation centers, causing small stepped pyramids to appear on the surface. Comparison with step-flow experiments on copper vicinal surfaces substantiates the hypothesis that many previously unexplained features of the meandering instability in this system are due to impurities. An ab initio density functional theory study of oxygen and CO adsorption is reported, giving further support to the impurity scenario.