Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 107: Semiconductor Surfaces (joint session O/HL)
O 107.1: Talk
Thursday, March 19, 2020, 15:00–15:15, REC C 213
Time-resolved reflection anisotropy spectroscopy reveals the impact of surface non-idealities for water adsorption on GaP — •Matthias M. May1, Helena Stange1, Jonas Weinrich2, Thomas Hannappel3, and Oliver Supplie3,4 — 1Helmholtz-Zentrum Berlin, Germany — 2Ferdinand-Braun-Institut, Berlin, Germany — 3Technische Universität Ilmenau, Germany — 4Humboldt-Universität zu Berlin, Germany
The initial interaction of water with semiconductor surfaces typically leads to surface chemical reactions, which determine the electronic structure of the solid–liquid interface as well as stability against corrosion. Access to this interface to reveal the nature of the interaction is, however, challenging. Here, we study gallium phosphide-based (100) surfaces exposed to H2O by means of time-resolved reflection anisotropy spectroscopy during water adsorption in vacuum [1]. We show that the introduction of imperfections in the form of surface steps via substrate off-cut variation or trace contaminants not only changes the dynamics of the interaction, but also its qualitative nature. While the clean surface without steps does not show any presence of oxygen after several 10 kL of exposure at room temperature, this changes with the introduction of trace carbon or a substrate off-cut. The decay rate of the surface optical anisotropy allows us to estimate activation energies of the surface reactions. Our findings emphasise the challenges for the comparability of experiments with idealised electronic structure models.
[1] May et al., SciPost Physics 6, 058 (2019).