Blue, green and red cathodoluminescence of Y2O3 phosphor films prepared by spray pyrolysis

Thin films of yttrium oxide doped separately with Eu3+, Tb3+ and Tm3+ were deposited by spray pyrolysis. The effect of preparation conditions on the structural and cathodoluminescent (CL) properties of the thin films was investigated. Films containing Eu3+, Tb3+ and Tm3+ emitted red, green and blue colors, respectively. Films of yttrium oxide doped with Tm were evaluated in detail. The blue emission of these films had CIE chromaticity coordinates of x=0.158 and y=0.150 with a dominant wavelength of 476 nm and a color purity of 78% compared to CIE Standard Source C. The CL intensity of the films under 5 kV beam excitation and a current density of 5 mA/cm2 depended strongly on annealing conditions and thulium doping concentration. For Tm-doped films the maximum luminance was 30.4 cd/m2 and there was a linear relationship between the CL intensity and excitation voltage. A luminance of 255 cd/m2 was obtained for the Eu-doped film. The dominant wavelength was 604 nm with 100% purity, and x=0.645 and y=0.357. The luminance for the Tb-doped film was 72 cd/m2 with a dominant wavelength of 547 nm and 77% purity.