Regensburg 2000 – wissenschaftliches Programm

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.15: Poster

Montag, 27. März 2000, 19:00–22:00, Bereich C

The influence of strain on diffusion of Si dimers on Si(001) — •Erwin Zoethout, O. Gurlu, H.J.W. Zandvliet, and Bene Poelsema — Department of Applied Physics and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands

The influence of lattice-mismatch induced tensile strain on the

diffusion of Si dimers on Si(001) surfaces has been studied with

scanning tunneling microscopy in a temperature range from

300 to 350 K. The tensile strained surface has been obtained by

epitaxially growing about one monolayer of Si on a Ge(001)

substrate. A few percent of a monolayer is deposited on the

strained or the bare Si(001) surface in order to investigate

surface diffusion. The surface diffusion can be divided into two

main pathways: one along and one across the surface dimer rows.

The rates of diffusion along the substrate dimer rows turn out

to be almost insensitive to tensile strain, whereas the rates of

diffusion across the substrate dimer rows are significantly

enhanced. The weak dependence of the along row diffusion rate

on tensile strain is attributed to the presence of a

dissociative intermediate state of the ad-dimer during diffusion

rather than diffusion as a unit.