Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 8: Solid-liquid interfaces: Structure, Spectroscopy I

O 8.6: Talk

Monday, March 12, 2018, 11:45–12:00, MA 144

GaP(100) in contact with water: Reflection anisotropy spectroscopy from first principles — •Matthias M. May and Michiel Sprik — Univeristy of Cambridge, Department of Chemistry

Surfaces of III-V semiconductors in contact with an electrolyte are not only relevant for applications such as solar water splitting, but also offer the opportunity to correlate experiments on well-defined surfaces with theory. Here, we study the P-rich surface of GaP(100), which shows an extraordinary stability against oxidation from gas-phase water. While its surface ordering is modified by exposure to water as evidenced by in situ reflection anisotropy spectroscopy (RAS), no traces of oxygen could be found by experiment.[1] Modelling the surface with density functional theory and deriving RAS, we find evidence for a water-induced hydrogen-rich surface phase. [2] We furthermore extend this work towards RAS in a bulk electrolyte by investigating the influence of finite electric fields and potentials [3] on the optical anisotropy in the Helmholtz layer.
May et al, NJP 15:103003 (2013). [2] May and Sprik, arXiv:1710.08194. [3] Zhang and Sprik, PRB 94:245309 (2016).