Preparation and luminescent properties of Eu-doped Ln2O3 (Ln = Gd, Lu) thin film by citrate sol–gel process

Ln2O3:Eu (Ln=Gd, Lu) luminescent thin films were deposited on sapphire and Si substrates using citrate sol–gel technique. The prepared films in different process conditions were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) measurement. The influence of viscosity, heating rate and annealing atmosphere on the morphology of Ln2O3:Eu films were discussed in detail. It is indicated that crack-free films could be prepared after sintering at temperatures ranging from 500–1100 °C with heating rate of 2.5 °C/min. The photoluminescence properties of the films were highly dependent on the annealing atmosphere, and the highest emission intensity was obtained for the sample by annealing in water vapor/oxygen atmosphere.