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O: Fachverband Oberflächenphysik

O 6: Semiconductor substrates: Adsorption

O 6.4: Vortrag

Montag, 14. März 2011, 12:00–12:15, WIL B122

Adsorption dynamics of ethylene on Si(001) — •Marcus Lipponer¹, Nico Armbrust¹, Michael Dürr^1,2, and Ulrich Höfer¹ — ¹Philipps Universität, D-35037 Marburg — ²Hochschule Esslingen, D-73728 Esslingen

The functionalization of semiconductor surfaces by means of organic molecules is of great interest due to possible applications in the field of nanoelectronics. However, only little information on the reaction dynamics of these systems is available. In this work, the adsorption dynamics of ethylene on Si(001) has been investigated. With ethylene being the most simple unsaturated organic molecule, the system serves as a model system for non-activated adsorption on semiconductor surfaces. In order to investigate its reaction dynamics, we employed a supersonic molecular beam which allows for the control of the kinetic energy of the impinging molecules. Additionally, surface temperature and the excitation of internal degrees of freedom were varied when measuring the sticking coefficients as a function of relative surface coverage by means of King and Wells techniques. With increasing kinetic energy of the impinging molecules, we find a decrease of the initial sticking coefficient as it is typical for non-activated reaction channels; with increasing surface temperature a decrease of the initial sticking coefficient is observed. Surprisingly, the maximum surface coverage also decreases with increasing surface temperature. The excitation of the internal degrees of freedom is shown to have a minor impact on the reactivity. The results are discussed in the context of a reaction channel via a mobile precursor.