The Fermi energy in oxides: assessing and understanding the limits using XPS
March 10-14, 2019
The Fermi energy in semiconductors can often be freely controlled across the whole energy gap by doping. This is not the case in oxides, where different mechanisms exist, which can limit the range of the Fermi energy. These limits can be caused by i) dopants having deep rather than shallow charge transition levels, ii) self-compensation where the Fermi energy dependence of the defect formation energy leads to spontaneous formation of compensating defects, iii) the change of the oxidation state of either the cations or the oxygen. The latter is particularly relevant for compounds with transition metal or rare earth cations and has been recently demonstrated to explain the low water splitting efficiency of hematite .
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Andreas Klein, N. Bein, C. Castro Chavarria, R. Giesecke, Y. Hermanns, B. Huang, S. Kashiwaya, C. Lohaus, K. Schuldt, H. Wardenga, and W. Jaegermann, "The Fermi energy in oxides: assessing and understanding the limits using XPS" in "Nonstoichiometric Compounds VII", ECI Symposium Series, (2019). https://dc.engconfintl.org/nonstoichiometric_vii/56