SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 90: Poster Session VII: Surface reactions I
O 90.6: Poster
Donnerstag, 4. März 2021, 10:30–12:30, P
Impact of atomic hydrogen on decomposition reactions of SiO2 layers on Si(100): a LEEM study — •Jonas Darius Fortmann1,2, Gerhard Lilienkamp1, and Winfried Daum1 — 1Institute of Energy Research and Physical Technologies, TU Clausthal, Leibnizstraße 4, 38678 Clausthal-Zellerfeld, Germany — 2Department for Physics, Experimental Physics, Universität Duisburg-Essen, Lotharstr. 1-21, 47057 Duisburg, Germany
Clean and well-ordered Si surfaces can be obtained by annealing Si wafers covered with a thin, protective layer of SiO2 in UHV. Tromp et al. first showed that the decomposition of thermally grown SiO2 layers on Si(100) upon annealing occurs in form of square-like voids appearing spontaneously or at defects [1]. Accordingly, diffusion of Si monomers from the voids to the reaction fronts and their reaction with SiO2 at the interface are crucial elements of the decomposition process. In this study, we used LEEM to investigate the impact of atomic hydrogen on decomposition reactions of thermally grown and native surface films of SiO2 on Si(100). For 10 nm thermal oxide, the presence of atomic hydrogen leads to voids of highly irregular shape with crack-like extensions of the reaction fronts into the surface oxide. Moreover, the growth rates of these voids at 900∘C are much higher than those found in comparative experiments without hydrogen. In contrast, atomic hydrogen reduces the growth rates of more circular voids in 2 nm native SiO2 layers on Si(100) at 790∘C. The different impact of atomic hydrogen for native and thermal surface oxides will be discussed. [1] R. Tromp et al., Phys. Rev. Lett. 55, 2332 (1985).