Properties of Eu-doped YVO4 thin films grown on glass substrates by radio-frequency magnetron sputtering

Abstract

The effects of substrate temperature on the structural, morphological and luminescent properties of YVO4:Eu3+ phosphor thin films were investigated using X-ray diffraction, field emission scanning electron microscopy, photoluminescence spectrometry and ultraviolet–visible spectrophotometry. YVO4:Eu3+ thin films were grown on glass substrates using a radio-frequency magnetron sputtering technique at varying substrate temperatures of 25–400 °C. All thin films exhibited a strongly (200) preferred orientation. The optical transmittance spectra indicated an average transmittance higher than 86.5% in the range of 400–1100 nm. Regardless of the substrate temperature, five emission bands centered at 542, 598, 622, 656 and 705 nm, respectively, were observed for all thin films. The maximum excitation and emission spectra were observed at a substrate temperature of 400 °C. A red shift of the band gap energy was observed with increasing substrate temperature. The intensity of the red emission from 5D0 → 7F2 (622 nm) electric dipole transition was stronger than that of the orange emission due to 5D0 → 7F1 (598 nm) magnetic dipole transition, which indicates the presence of more Eu3+ ions in sites without inversion symmetry. Therefore, substrate temperature plays an important role in the growth of red-emitting YVO4:Eu3+ thin films for solid-state lighting and electroluminescent devices.