Band-to-band transition energy parameters for single-crystal actinide samples of uranium oxide and thorium oxide were determined and compared using spectroscopic ellipsometry and critical-point dielectric function analyses. Spectroscopic ellipsometry measurements from the near-infrared to the vacuum ultraviolet spectral region were used to determine the dielectric functions of uranium oxide and thorium oxide. The critical-point structure is similar between UO2 and ThO2 but strongly blue shifted for ThO2. We find bandgap energies of 2.1 eV and 5.4 eV for UO2 and ThO2, respectively.
Applied Physics Letters
A. Mock, C.L. Dugan, S. Knight, R. Korlacki, J.M. Mann, M.M. Kimani, J.C. Petrosky, P.A. Dowben, and M. Schubert, Appl. Phys. Lett. 114, 211901 (2019). https://doi.org/10.1063/1.5087059