XANES and XEOL Investigation of Cerium and Terbium Co-Doped Silicon Oxide Films

The luminescent and structural properties of cerium and terbium co-doped silicon oxide thin films were investigated through transmission electron microscopy, photoluminescence spectroscopy, and synchrotron-based X-ray absorption spectroscopy. While combined blue and green luminescence characteristic of Ce3+ and Tb3+ ions, respectively, was observed from different compositions of films, the emission intensity from samples in which Ce2Si2O7 nanocrystallites were formed after high temperature annealing was much stronger than in films where the Ce and Tb co-dopants were incorporated in an amorphous SiO2 host matrix. Films containing the cerium silicate phase also exhibited a very strong enhancement of Tb emission. X-ray absorption near edge structure and X-ray excited optical luminescence analysis at the Si L-3,L-2-, Si K-, O K-, Ce N-4-, and Ce M-5,M-4-edges indicated this enhancement was likely the result of a direct energy transfer process between the cerium silicate and Tb levels.