Optical, Luminescent, and Structural Properties of Highly Transparent Yttrium Oxide Thin Films Doped with Europium

Abstract

Highly transparent yttrium oxide thin films doped with europium (Y₂O₃:Eu) were fabricated and their optical, luminescent, and structural properties were investigated. Thin films of Y₂O₃:Eu were deposited on fused quartz substrates by using a radio-frequency (RF) magnetron sputtering method and subsequently annealed at 1000 °C for 1 hour in air atmosphere. The resultant Y₂O₃:Eu films showed a high optical transmittance, greater than 82%, in the visible wavelength range above 400 nm and up to 92% transmittance in the near-infrared range. The optical band gap of the films was determined to be approximately 5.77 eV. The refractive index of the films ranged between 1.854 and 1.767 in the visible wavelength region from 400 to 700 nm. X-ray diffraction (XRD) measurements revealed that the films had a cubic crystal structure of Y₂O₃ and were strongly textured along the [100] direction. The Y₂O₃:Eu films exhibited a red photoluminescence emission with a dominant peak centered at around 612 nm due to the ⁵D₀ → ⁷F₂ transition of Eu³⁺ ion. The excitation spectrum showed a broad band in the ultraviolet (UV) wavelength region corresponding to the O²⁻−Eu³⁺ charge transfer band.