Enhanced luminescent characteristics of laser-ablated GdVO4:Eu3+ thin films by Li-doping

Li-doping has been used to improve luminescent characteristics of thin films. Influence of Li-doping on the crystallization, surface morphology and luminescent properties of GdVO4:Eu3+ films have been investigated. Crystallinity and surface morphology of thin films have been very important factors to determine luminescent characteristics and depended on the deposition conditions. The GdVO4:Eu3+ and Li-doped GdVO4:Eu3+ thin films have been grown using pulsed laser deposition method on Al2O3 (0 0 0 1) substrates at a substrate temperature of 600 °C under an oxygen pressure of 13.33-53.33 Pa. The crystallinity and surface morphology of the films were investigated using X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. A broadband incoherent ultraviolet light source with a dominant excitation wavelength of 310 nm and a luminescence spectrometer have been used to measure photoluminescence spectra at room temperature. The emitted radiation was dominated by the red emission peak at 619 nm radiated from the transition of 5D0-7F2 of Eu3+ ions. Particularly, the peak intensity of Li-doped GdVO4 films was increased by a factor of 1.7 in comparison with that of GdVO4:Eu3+ films. The enhanced luminescence results not only from the improved crystallinity but also from the reduced internal reflections caused by rougher surfaces. The luminescent intensity and surface roughness exhibited similar behavior as a function of oxygen pressure.