Germanium Growth Orientation On Srtio3 (001) 2 X 1 Surface: Role Of Surface Reduction

We present a theoretical study of germanium growth orientation dependence on SrTiO3 surface structure using first-principles calculations. Contrary to much work on the SrTiO3 surface which considers the simple TiO2 termination, we work on the now well known 2 x 1 reconstructed surface, which is terminated with a TiO2 double layer.(29) We study the oxygen reduction at this surf ace maintaining the 2 x 1 reconstruction Analysis of its electronic structure shows that the reduction leads to a metallic surface and changes of the surface bond characteristics. Therefore, the growth routes for Ge epitaxy are studied. It is demonstrated that the reduction favors the creation of the Ge-O bonds by weakening the strength of the Ti-O bonds. It gives the possibility of Ge[001] growth direction, which is not possible on a nonreduced surface.