[Effect of post-annealing on the structure and fluorescence properties of YMnO3 thin films]

YMnO3 thin films deposited on Si (100) substrate by pulsed laser deposition at room temperature were annealed at different temperatures. The microstructure and fluorescent emission properties of these films were studied using XRD and UV-Vis spectroscopy. The results show that polycrystalline YMnO3 thin films can be obtained through post-annealing, in which hexagonal phase and orthorhombic phase coexist. And with increasing the temperature, the ratio of orthorhombic phase to hexagonal phase varies considerably. The results also show that fluorescence peaks in the wavelength range of 430-620 nm maybe originate from the transition from 5T2 to 5E of Mn3+. The intensity of fluorescence peaks is enhanced with increasing the temperature. However, the positions of fluorescence peaks remain invariable. These results indicate that the change in the film structure affects the transition probability greatly but almost has no effect on the position of energy level. Meanwhile, the relative intensity ratio of cyan fluorescence peak to green fluorescence peak is almost unchanged.