Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 38: Adsorption an Oberflächen III

O 38.2: Vortrag

Donnerstag, 11. März 2004, 16:00–16:15, H38

Atomically resolved diffusion processes of hydrogen on Si(001) induced by nanosecond heating pulses — •C. Schwalb, M. Lawrenz, M. Dürr, and U. Höfer — Fachbereich Physik, Philipps-Universität, D-35032 Marburg

The rearrangement of silicon dangling bonds following pulsed laser heating of monohydride-covered Si(001) surfaces has been studied with scanning tunneling microscopy (STM). Laser-induced thermal desorption (LITD) of small amounts of H2 via the so-called interdimer pathway leads to the creation of isolated pairs of dangling bonds at two adjacent dimers [1]. Hydrogen diffusion causes this arrangement of dangling bonds - which represents an excited state of the surface - to change quickly into the equilibrium configuration consisting of dangling bonds paired up at a single dimer. By using multiple nanosecond heating pulses we were able to freeze the surface at various stages of the equilibration process and take snapshots with the STM. In this way we were able to monitor hydrogen diffusion processes with atomic resolution which are associated with rates as high as 108   s−1 .

[1] M. Dürr et al., Science 296, 1838 (2002).

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