Role of Codeposited Impurities in Growth: Explaining Cu(0 0 1)

A unified explanation of the physics underlying all the distinctive features of the growth instabilities observed on Cu vicinals\footnote{N. N$\acute{\mbox{e}}$el $\ldots$ H.-J. Ernst., J. Phys.: Condensed Matter 15, S3227 (2003).} has long eluded theorists. Recently, kinetic Monte Carlo studies showed that codeposition of impurities during growth could account for all the experimental observations.\footnote{A. Ben-Hammouda et al., Phys. Rev. B 77, 245430 (2008).} To identify the responsible impurity atom, we compute the nearest-neighbor binding energies ($E_{NN}$) and terrace diffusion barriers ($E_d$) for several candidate impurity atoms on Cu(1 0 0) using DFT-based VASP. Our calculations show that codeposition (with Cu) of mid-transition elements, such as Fe, Mn, and W, could cause the observed instabilities; when the experimental set-up is considered, W emerges to be the most likely candidate. We discuss the role of impurities in nanostructuring of surfaces.