Optical and Luminescent Properties of Highly Oriented Nanocrystalline Gd_2-xEu_xO₃ Thin Films

Abstract

Highly crystalline and transparent Eu-doped Gd 2 O 3 thin films were produced through a modified sol-gel method that did not require the use of any chelating agent. The effect of the atomic fraction of Eu 3+ ions ('x' =0.05-0.30) on the structural, optical and luminescent properties has been studied. X-ray diffraction studies showed the preferential growth of Gd 2-x Eu x O 3 thin films along the (400) plane corresponding to the cubic phase. UV-vis measurements revealed the high film transparency of the films in the visible region and a band gap value of 5.3eV. It has also been observed that the luminescence properties of the films were strongly dependent on both, the excitation wavelength and Eu concentration; the most efficient excitation conducive to red luminescence was achieved at the absorption band of Gd 2 O 3 host (229nm). Under this condition all films exhibited strong red emission that is characteristic of Eu 3+ ions. The emission intensity was also dependent on the doping level; the most intense luminescence was obtained at 'x'=0.15. The drop in the luminescence intensity observed for 'x' values higher than 0.15 was attributed to quenching concentration effect.