Effects of substrate temperature on the structure and luminescence of transparent red-emitting Eu-doped Y2O3 thin films

Transparent red-emitting Eu-doped Y 2 O 3 thin films were deposited by radio frequency magnetron sputtering and the effects of substrate temperature on their structure and luminescence were investigated. X-ray photoelectron spectroscopy measurements showed that the stoichiometric Y 2 O 3 was formed and the Eu ions were incorporated mainly in the form of Eu 3+ in the films. The Y 2 O 3 :Eu films had a mixed crystalline structure consisting of monoclinic and cubic phases at low substrate temperatures. A single phase of cubic structure was obtained at substrate temperatures above 300 °C and the films were preferentially oriented along the [111] direction. The Y 2 O 3 :Eu films deposited at room temperature were under residual compressive strain, which was decreased with increasing substrate temperature. The Y 2 O 3 :Eu films showed the photoluminescence with the most intense peak at 613 nm which originated from the transition between the 5 D 0 and 7 F 2 states in Eu 3+ ions. The PL intensity was increased and the spectral linewidth was decreased with increasing substrate temperature. All the Y 2 O 3 :Eu films showed good transparency with an optical transmittance greater than 80% in the wavelength region from 400 to 1100 nm. The transmittance of the Y 2 O 3 :Eu films was decreased as the substrate temperature increased, which was due to the increased surface roughness of the films.