Theoretical evidence concerning mixed dimer growth on the Si(001)(2x1) surface

Published in J. Phys.: Condensed Matter 8, 6641 (1996)

S.J.Jenkins and G.P.Srivastava

Semiconductor Physics Group, Department of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom

The local atomic geometry, chemical bonding and energetics for half- and full-monolayer Ge coverages on the Si(001)(2x1) surface have been studied by applying the ab initio pseudopotential method. For one monolayer coverage we find that the adatoms form an asymmetric dimer with length equal to the bond length in bulk Ge. At half monolayer coverage we find that the formation of mixed Si-Ge dimers is preferable to growth of Ge-Ge dimers in islands, confirming recent experimental observations. Our work also shows that Ge diffusion into the substrate will only become important at unusually high growth temperatures, in the region of 1000 K or above.

Stephen Jenkins
Last modified: Fri Dec 6 14:18:50 GMT 1996