| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 89 === The Study of Blue ZnGa2O4 Phosphor for Field EmissionDisplay by Chemical Precipitation Method
Heng-Cheng Huang *, Meiso Yokoyama**, Shoou-Jinn Chang** Department of Electrical Engineering
National Cheng Kung University
Tainan, Taiwan, ROC
Abstract
In this thesis, we research and produce the low voltag e ZnGa2O4 phosphor of field emission displays (FED) by chemical precipitation method. The parameters of chemical precipitation method , such as the PH value on the first stage and the second stage of chemical precipitation process、the optimum firing temperature were investigated systematically . At the some time, the phosphor deposited on ITO glass substrate by electrophoretic deposition method, in order to improve the luminance intensity, efficiency and stability of the phosphor layer.
In this experiment, because it is difficult for Zn and Ga to coprecipitate in a solution at one time, we divided into two stages to prepare the ZnGa2O4 phosphor.
The first stage on the chemical reaction process is acid – base reaction, the precipitate from the reaction is GaOOH. The second stage is that filtered the precipitate (GaOOH) which precipitated at the first stage, and then added the precipitate into the reactant of the second stage. The phosphor would be precipitated slowly by adding diethylamine to adjust the PH value. Then we sintered the phosphor prepared by chemical precipitation method at different temperatures in order to get complete crystallization. From the experiment results, we find the optimum PH value ( PH=8 ) on the first stage and PH=8.5 on the second stage. Moreover, From the X-ray diffraction results, the crystallization of the phosphor had took place completely at 8000C ~ 10000C. The formation temperature of ZnGa2O4 phosphor by chemical precipitation method was lower than that of the conventional solid-state reaction method. Consequently, the cost of facility could be reduced.
The measurement of cathodoluminescent intensity was executed at a beam voltage of 5 kV and a current of 30μA in a vacuum pressure of 8.2 ×10-8 torr. We found the optimum cathodoluminescent intensity of 2361 cd/m2 was obtained for the phosphor produced by chemical precipitation method ( 1st: PH=8 & 2nd: PH=8.5 ) fired at 10000C。Furthermore, it can be observed that the color coordinates of phosphor are X=0.165, Y=0.132 in this experiment.
*The author **The advisor
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