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DS: Dünne Schichten
DS 7: Schichtwachstum I
DS 7.6: Vortrag
Montag, 26. März 2001, 16:30–16:45, S 13/14
Growth of (110) Diamond using pure Dicarbon — •Michael Sternberg1, Markus Kaukonen2, Thomas Frauenheim1, and Risto Nieminen2 — 1Theoretische Physik, Universität Paderborn. — 2Laboratory of Physics, Helsinki University of Technology.
We use a density-functional based tight-binding method to study diamond growth steps by depositing dicarbon species onto a hydrogen-free diamond (110) surface. C2 molecules are deposited on an initially clean surface, in the vicinity of a growing adsorbate cluster, and finally, near vacancies just before completion of a new monolayer. Preferred growth stages arise from C2n clusters in near ideal lattice positions forming zigzag chains running along the [110] direction parallel to the surface. The adsorption energies are consistently exothermic by 8–10 eV per C2. Surface diffusion simulations of C2 molecules near existing adsorbate clusters reveal migration barriers in excess of 3 eV on the clean surface, and 0.6–1.0 eV on top of graphene-like adsorbates. The results indicate that growth from dicarbon proceeds either by direct adsorption onto clean sites or after migration on existing C2n chains. Intermediate surface graphitisation occurs, but is healed by rebonding without barriers, such that diamond growth is favoured.