Annealing effect on photoluminescence properties of Er doped Al2O3–SiO2 sol–gel films

Abstract Annealing effect on photoluminescence intensity of Er doped Al 2 O 3 –SiO 2 prepared from Er doped boehmite (AlOOH) and GPS (3-glycidoxypropyltrimethoxysilane) hybrid was investigated. The emission intensities peaked at 1.54 μm, which correspond to the 4 I 13/2 → 4 I 15/2 transition of the Er 3+ ion, are greatly increased by about 8 times between 900 and 1000 °C, than that expected from TGA associated with the elimination of hydroxyl groups which is responsible for the fluorescence quenching. The residual hydroxyl groups for Er doped Al 2 O 3 –SiO 2 after annealing at high temperature was further analyzed by FT-IR. Finally, fluorescence intensities were compared with the variation of BET surface areas against the annealing temperature. It was found that photoluminescence intensity below 1000 °C was more dependent on surface hydroxyl groups re-adsorbed by a high specific surface area rather than internal hydroxyl groups remained in gel film.