THE INITIAL-STAGE OF EPITAXIAL-GROWTH OF GE ON GE(111) AS STUDIED BY X-RAY-DIFFRACTION

We present an in situ X-ray scattering study of the evolution of surface structure and morphology during deposition of Ge on Ge(111). The substrate temperature (300 K) was such that the growth proceeds through two-dimensional nucleation. We determined the sites on the c(2 x 8) reconstructed Ge(111) surface to which the first deposited Ge atoms bond. The arrangement of the deposited atoms was inferred from an analysis of the diffracted intensities along the integer-order rods of Bragg scattering perpendicular to the surface plane. We find the first deposited Ge atoms to occupy adsorption sites above the "rest atoms" in the reconstructed unit cell. For higher coverages islands of bilayer height are formed.