Structure, morphology, and luminescent behavior of RE 3+ -doped GdVO 4 thin films

This report focuses on fabrication, characterization, and fundamental optical properties of Eu 3+ - and Sm 3+ -doped GdVO 4 luminescent thin films. Films were uniformly grown on three different substrates: single crystal sapphire (0001), thermally grown silicon oxide (Si/SiO 2 ~ 500 nm) on silicon and fused quartz using pulsed laser deposition technique. Thin films’ structure, morphology, and photoluminescent properties were investigated by X-ray diffraction, atomic force and scanning electron microscopy, diffuse reflectance and photoluminescence spectroscopy. Thin films’ structure characterized by X-ray diffraction showed that for all substrates highly crystalline, zircon-type pure phase films were formed. Films’ thickness and internal morphology were determined by cross-sectional scanning electron microscopy showing completely dense, pore-free film with an average thickness of ~ 390 nm. Atomic force microscopy revealed that the average crystallite size of both Eu 3+ - and Sm 3+ -doped GdVO 4 thin films deposited on fused quartz is higher as compared to the single crystal sapphire (0001) and thermally grown silicon oxide (Si/SiO 2 ~ 500 nm) and that the surface roughness increases with the increase in the grain size. Energy band gap values, estimated from diffuse reflectance spectra were 3.57 and 3.53 eV for Eu 3+ - and Sm 3+ -doped GdVO 4 thin films, respectively. Photoluminescent properties were investigated in detail in both steady state and lifetime domain. The emission spectra show clear orange–red emission in the Sm 3+ -doped GdVO 4 thin films and red emission in Eu 3+ -doped ones.