Fermi level and current transport of Bi12GeO2

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Abstract
A photoelectrochemical resistor was constructed using a bismuth germanium oxide electrode and a liquid junction. Current transport consists of the oxidation and reduction of water by holes and electrons, and the device exhibits ideal current voltage characteristics with a ratio of light to dark current greater than 104. By comparison of the flat‐band potential in the dark and under irradiation it is concluded that the intrinsic Fermi level of our sample is in the center of the band gap at −310 mV vs SCE (pH=5). Deep trap levels at 0.20 and 0.33 eV above the valence band can be present in varying concentrations and facilitate the trapping and recombination of electrons and thereby decrease conductivity.