Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 73: Semiconductor Surfaces (joint session O/HL)

HL 73.1: 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 Supplie^3,4 — 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).