Electroreflection measurements on semiconductor/electrolyte interfaces to determine the voltage distribution

The electroreflectance signal from a semiconductor electrode surface is sensitive to the magnitude of the space charge. It is used to determine the voltage distribution between the space-charge layer and the Helmholtz double layer at an electrode/electrolyte interface. In this paper, the first of two, the authors describe the experimental arrangements and measurements of the electroreflectance spectra for n-MoSe sub(2) and n-WSe sub(2) under anodic and cathodic bias. Important features in the spectra are found to be in agreement with existing theories. Flatband values inferred from the electroreflectance spectra are in agreement with those from Mott-Schottky plots. The effects of Fermi level pinning on the electroreflectance spectra are demonstrated with n-GaAs.