Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 111: Oxides and Insulators: Adsorption II
O 111.4: Vortrag
Freitag, 16. März 2018, 11:15–11:30, MA 041
Temperature dependent initial sticking probability of Mg atoms on H:Si and SiO2 surfaces — •Miriam Fritscher1, Ulrich Hagemann2, and Hermann Nienhaus1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Duisburg — 2Interdisciplinary center for analytics on the nanoscale (ICAN), CENIDE, Duisburg
The temperature dependence of the initial sticking probability of magnesium atoms evaporated from a Knudsen-cell onto hydrogen passivated silicon (H:Si(111)) and silicon dioxide (SiO2)substrates is investigated. Mg is evaporated stepwise onto both surfaces simultaneously and X-ray photoelectron spectra are recorded after each step to determine the growth rate of the Mg film. This is done at variable substrate temperatures between 140 K and room temperature. It was found that the sticking probability of Mg atoms is approximately the same for both surfaces at low temperatures (T<210 K), whereas for room temperature it reaches zero for the SiO2 substrate. The temperature dependence of the sticking probability on Si surfaces is significantly smaller. Furthermore, the reduction of the sticking probability on SiO2 at room temperature is not dependent on the thickness of the SiO2 film. Experiments indicate that a single monolayer of SiO2 on Si results already in the dramatic decrease of the sticking probability. Once Mg atoms are sticking to the substrate they form islands and do not desorb again. A simple precusor mediated sticking-desorption model is applied to explain the findings.