Si-Ge Intermixing and the 5x5-(111) Surface Reconstruction

We present \textit{ab initio} results of the energetics and structure of a Si(111)-5x5 slab with two bilayers of Ge(5x5) adsorbed on it. We explore the aspects of this Si-Ge surface structure with those of an analogous pure Ge(111)-5x5 slab and we note many important differences such as the larger corrugation of the adatom heights in the former compared with the latter. \textit{Ab initio} results are also obtained for the effects of Si-Ge intermixing at the Si-Ge interface. These shed light on this transport mechanism as a way of lowering the strain.