Structure and optical properties of ZnO/Zn2SiO4 composite thin films containing Eu3+ ions

ZnO and ZnO/Zn2SiO4 thin films doped with 3% Eu3+ ions were prepared through sol-gel dip-coating and subsequently thermal annealing in the range of 600-900 °C. Effects of zinc and silica concentration on the structure and optical properties of these thin film specimens were investigated using thermogravimetric differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and emission spectroscopy. Transparent thin films containing ZnO nanocrystals and Zn2SiO4 nanocrystals were fabricated. It was found that Eu3+ ions were mainly resided in the amorphous matrix or the surface of the nanocrystals, instead of being incorporated into the nanocrystals. As a result, these composites showed intense red emission from Eu3+ ions upon 394 nm light emission, and violet emission at ~380 nm upon 266 nm light excitation.