Get access

Solar Hydrogen Generation with Wide-Band-Gap Semiconductors: GaP(100) Photoelectrodes and Surface Modification

Authors

  • Dr. Bernhard Kaiser,

    Corresponding author
    1. Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    • Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    Search for more papers by this author
  • Dominic Fertig,

    1. Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    Search for more papers by this author
  • Jürgen Ziegler,

    1. Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    Search for more papers by this author
  • Joachim Klett,

    1. Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    Search for more papers by this author
  • Dr. Sascha Hoch,

    1. Evonik Industries AG, Creavis Technologies & Innovation, Paul-Baumann-Straße 1, 45772 Marl (Germany)
    Search for more papers by this author
  • Prof. Dr. Wolfram Jaegermann

    Corresponding author
    1. Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    • Center of Smart Interfaces and Institute for Materials Science, Technische Universität Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)
    Search for more papers by this author

Abstract

GaP, with its large band gap of 2.26 eV (indirect) and 2.78 eV (direct), is a very promising candidate for direct photoelectrochemical water splitting. Herein, p-GaP(100) is investigated as a photocathode for hydrogen generation. The samples are characterized after each preparation step regarding how their photoelectrochemical behavior is influenced by surface composition and structure using a combination of electrochemical and surface-science preparation and characterization techniques. The formation of an Ohmic back contact employing an annealed gold layer and the removal of the native oxides using various etchants are studied. It turns out that the latter has a pronounced effect on the surface composition and structure and therefore also on the electronic properties of the interface. The formation of a thin Ga2O3 buffer layer on the p-GaP(100) surface does not lead to a clear improvement in the photoelectrochemical efficiency, neither do Pt nanocatalyst particles deposited on top of the buffer layer. This behavior can be understood by the electronic structure of these layers, which is not well suited for an efficient charge transfer from the absorber to the electrolyte. First experiments show that the efficiency can be considerably improved by employing a thin GaN layer as a buffer layer on top of the p-GaP(100) surface.

Get access to the full text of this article

Ancillary