The effect of different annealing temperatures on the structure and luminescence properties of Y2O3:Bi3+ thin films fabricated by spin coating

Abstract

This paper reports on the structural, morphology and optical properties of Y2−xO3:Bix=0.005 micro-and nanophosphors synthesized via the spin coating method. The influence of different annealing temperatures (900–1200°C) on the morphology, crystal structure and the photoluminescence (PL) properties of the synthesized films were studied in detail. The crystal structure of the films was investigated with X-ray diffraction. The presence of the three major diffraction peaks with Miller indexes (211), (222) and (400) indicated that the Y2−xO3:Bix=0.005 thin films were well-crystallized at 900°C, 1000°C, 1100°C and 1200°C. Additionally, extra diffraction peaks were observed for the sample that was annealed at 1200°C. Those extra peaks were due to the formation of the Y2Si2O7 phase owing to the annealing induced changes in the crystal structure and chemical composition of the Y2−xO3:Bix=0.005 thin film. This may also be attributed to inter diffusion of atomic species between the Si substrate and the Y2−xO3:Bix=0.005 thin film at the high annealing temperature. Due to structure-sensitive properties of the Bi3+ ions, a blue shift of the centre PL emission band from 495nm to 410nm was clearly observed and explained in detail. The time-of-flight secondary ion mass spectroscopy results show the Si diffusion from the Si substrate, whereas, the scanning electron microscopy and the atomic force microscopy were used for the morphology analysis.