Critical role of the surface reconstruction in the thermodynamic stability of {105} Ge pyramids on Si(001)

We show by molecular dynamics simulations on a scale comparable to experimental dimensions that a peculiar surface reconstruction of the {105} facets is responsible for the stability of Ge pyramids on Si(001). This finding is confirmed by ab initio total energy calculations for competing surface reconstructions and a very satisfactory comparison of the corresponding charge density maps to scanning tunneling microscopy measurements of the facets, both for filled and empty states