Water adsorption on the P-rich GaP(100) surface: Optical spectroscopy from first principles
Published version
Peer-reviewed
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Repository DOI
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Authors
Sprik, M
Abstract
The contact of water with semiconductors typically changes its surface electronic structure by oxidation or corrosion processes. A detailed knowledge
- or even control of - the surface structure is highly desirable, as it impacts the performance of opto-electronic devices from gas-sensing to energy conversion applications. It is also a prerequisite for density functional theory-based modelling of the electronic structure in contact with an electrolyte. The P-rich GaP(100) surface is extraordinary with respect to its contact with gas-phase water, as it undergoes a surface reordering, but does not oxidise. We investigate the underlying changes of the surface in contact with water by means of theoretically derived reflection anisotropy spectroscopy (RAS). A comparison of our results with experiment reveals that a water-induced hydrogen-rich phase on the surface is compatible with the boundary conditions from experiment, reproducing the optical spectra. We discuss potential reaction paths that comprise a water-enhanced hydrogen mobility on the surface. Our results also show that computational RAS - required for the interpretation of experimental signatures - is feasible for GaP in contact with water double layers. Here, RAS is sensitive to surface electric fields, which are an important ingredient of the Helmholtz-layer. This paves the way for future investigations of RAS at the semiconductor-electrolyte interface.
Description
Keywords
density functional theory, water, gallium phosphide, reflection anisotropy spectroscopy
Journal Title
New Journal of Physics
Conference Name
Journal ISSN
1367-2630
1367-2630
1367-2630
Volume Title
20
Publisher
IOP Publishing
Publisher DOI
Sponsorship
Engineering and Physical Sciences Research Council (EP/F038356/1)
Engineering and Physical Sciences Research Council (EP/P022596/1)
Engineering and Physical Sciences Research Council (EP/P022596/1)