Co on the H-passivated Si(001) surface: Density-functional calculations

We have presented an atomic and electronic structures, as well as chemical bonding of Co on the bare, partially H-passivated, and fully H-passivated Si(001)-(2×2) surface using density functional theory. There have been considered three different sites for Co on the surface; (1) an l-site (Co bonded to the lower lying Si-dimer component), (2) an h-site (Co bonded to the higher lying Si-dimer component), and (3) an i-site (intrarow position between adjacent Si dimer rows). The calculations indicate that for the i-site, the Co atom is located at nearly the same height as the Si dimers towards the vicinal region on the bare and partially H-passivated Si(001) surface. For all the remaining cases studied here, the Co atom prefers to stay at the subsurface site.