Cathodoluminescent characteristics of green-emitting ZnAl2O4 : Mn thin-film phosphors

Thin films of ZnAl2O4: Mn were grown on aluminosilicate ceramic plates using spray pyrolysis of aqueous solutions. The cathodoluminescence (CL) properties of the films under low to medium excitation voltage (< 5 kV) were investigated. The films exhibited green CL after being annealed at temperatures above 550 &DEG;C, which corresponds to the transition between T-4(1) and (6)A(1) of Mn2+ ions located in the tetra coordination of the Zn2+ site in the spinel structure. The chromaticity coordinates were x = 0.150 and y = 0.734 with a dominant wavelength of 525 nm and an 82% color purity. The CL luminance and efficiency depended on the excitation voltage and current density. Saturation effects were observed as the current density increased. A luminance of 540 cd/m(2) and an efficiency of 4.5 lm/W were obtained at an excitation voltage of 4 kV with a current density of 38 μA/cm(2).