ZnGa2O4 :Mn phosphors for thin-film electroluminescent displays exhibiting improved brightness

Thin films of ZnGa2O4:Mn were deposited by rf magnetron sputtering to study the effects of annealing temperatures less than 1000 C on the thin-film electroluminescent properties. EDAX showed a loss of zinc during sputtering, with the film composition being Zn0.9Mn0.03Ga2O4. All films showed strong (111) and (222) X-ray reflections relative to the power standard. As the annealing temperature was raised, the texture rotated towards that of the powder material. The as-deposited films showed no photoluminescence; however, once annealed at T greater than or equal to 750 C, a single emission band at 504 nm was observed. Emission wavelength was independent of annealing temperature. The electroluminescent brightness of the devices peaked at an annealing temperature of 900 C. Peak brightness and efficiency were 350 cd/m2 and 0.55 lm/W at 60 Hz, and 1500 cd/m2 and 0.30 lm/W at 600 Hz. These high brightness values were attributed to the roughness of the substrates. 31 refs.