Photoluminescence of Titanium-Doped Zinc Orthosilicate Phosphor Gel Films

Titanium-doped zinc orthosilicate (α-Zn2SiO4:Ti) phosphor thin films were deposited on silicon wafer substrates by the sol-gel process. The crystallization processes and photoluminescence properties of the films were investigated. X-ray diffraction revealed that the dried films were amorphous and converted into single-phase willemite structure following annealed at 600 deg. C and above. Upon thermal annealing at 800 deg. C - 1000 deg. C, Ti-doped willemite thin films had the average crystallite sizes of 17∼28 nm. The luminescence properties of phosphor films were characterized by excitation and emission spectra. Photoluminescence spectra of Ti-doped films exhibited prominent blue emission bands centered at 402 nm under an excitation wavelength of 225 nm. The emission intensity was dependent on the level of titanium doping, annealing temperature, and film thickness.