AUGER-ELECTRON DIFFRACTION STUDY OF THE INITIAL-STAGE OF GE HETEROEPITAXY ON SI(001)

The initial stage of pure and surfactant (Sb)-assisted Ge growth on a Si(001) surface has been studied by Auger electron diffraction (AED) a nd X-ray photoelectron diffraction (XPD). A single-domain Si(001)2 x 1 substrate was used to avoid the ambiguity arising from the usual doub le-domain substrate. For the pure Ge growth, 1 monolayer of Ge was dep osited onto the room temperature substrate followed by annealing at 35 0-degrees-C-600-degrees-C, which appeared to have (1 x 2) periodicity by LEED. Ge LMM AED patterns were measured to find that a substantial amount of Ge atoms diffuse to the bulk Si positions up to the fourth l ayer at least. For the Sb-assisted Ge growth, a Sb(1 x 2)/Si(001) surf ace was first prepared and Sb 3d XPD patterns were measured to find th at Sb forms dimers on the substrate. 1 ML of Ge was deposited onto the Sb(1 x 2)/Si(001) surface and then the surface was annealed at 600-de grees-C. Ge LMM AED and Sb 3d XPD patterns measured for this surface s howed that surfactant Sb atoms are indeed present on the first layer f orming dimers and that Ge atoms are present mainly on the second layer with a substantial amount of Ge diffused into the third and fourth la yers.