Influence of crystallisation on the photoluminescence properties of Y2-xErxTi2O7 sol-gel thin films

Optically active Er2Ti2O7 (ETO) and Y2-xErxTi2O7 (YETO) films have been successfully deposited using the aerosol-gel process. Several heat-treatment procedures are investigated in the 600–850 °C range. ETO and YETO films start to crystallise in the pyrochlore phase at about 750 °C, depending on the heat-treatment time. Crystalline YETO films form a solid solution where the erbium ions are well diluted. Up-conversion emission (UPE) in the visible wavelength range and infrared photoluminescence (PL) at 1.53 μm are investigated. PL spectra are composed of several sharp peaks. Stark splitting of the 4I13/2 and 4I15/2 erbium levels is analysed. A clear correlation between spectroscopic properties and film microstructure is evidenced. YETO films exhibit strong PL compared to ETO films. PL lifetimes of up to 8.6 ms were measured on YETO films at an erbium concentration of 2×1020 ions/cm3. The YETO compound is found to be a suitable material, improving the erbium active properties.

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