Water adsorption on the P-rich GaP(100) surface: Optical spectroscopy from first principles

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.

12 pages, 5 figures, 1 table

References in corpus (3)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Optimization Algorithm for the Generation of ONCV Pseudopotentials
• Efficient Direct Solar-to-Hydrogen Conversion by In Situ Interface Transformation of a Tandem Structure

Cited by in corpus (5)

• Combining experimental and computational methods to unravel the dynamical structure of photoelectrosynthetic interfaces
• The Interfacial Structure of InP(100) in Contact with HCl and H${}_2$SO${}_4$ studied by Reflection Anisotropy Spectroscopy
• The impact of non-ideal surfaces on the solid-water interaction: a time-resolved adsorption study
• The relevance of structural variability in the time-domain for computational reflection anisotropy spectroscopy at solid-liquid interfaces
• On the origin of bulk-related anisotropies in surface optical spectra