Optical absorption and spectral photoconductivity in α-(Fe 1-xCrx)2O3 solid-solution thin films
Hematite, α-Fe2O3, is an attractive narrow gap oxide for consideration as an efficient visible light photocatalyst, with significant potential for band gap engineering via doping. We examine optical absorption in α-(Fe1-xCrx)2O3 epitaxial films and explain the observed excitations, and the nature of the band gap dependence on x, through first-principles calculations. The calculated and measured optical band gap becomes smaller than that of bulk α-Fe 2O3 and reaches a minimum as the Cr cation fraction increases to 50%. The lowest energy transitions in the mixed-metal alloys involve electron excitation from occupied Cr 3d orbitals to unoccupied Fe 3d orbitals, and they result in a measurable photocurrent. The onset of α-Fe2O3 photoconductivity can be reduced by nearly 0.5 eV (to 1.60 eV) through addition of Cr. © 2013 IOP Publishing Ltd.
Publication Source (Journal or Book title)
Journal of Physics Condensed Matter
Chamberlin, S., Wang, Y., Lopata, K., Kaspar, T., Cohn, A., Gamelin, D., Govind, N., Sushko, P., & Chambers, S. (2013). Optical absorption and spectral photoconductivity in α-(Fe 1-xCrx)2O3 solid-solution thin films. Journal of Physics Condensed Matter, 25 (39) https://doi.org/10.1088/0953-8984/25/39/392002