Growth of ZnGa2O4 Phosphor by Radio Frequency Magnetron Sputtering.

ZnGa204 films have been prepared by radio frequency (RF) magnetron sputtering at various total pressure, RF power, and substrate temperatures. Microstructure and crystallographic orientation were characterized by x-ray diffraction. Surface morphologies were observed by scanning electron microscope. In addition, cathodoluminescence (CL) measurement was employed to observe the emission spectra of ZnGa204 films. The influences of various deposition parameters on the properties of grown films were studied. The optimum substrate deposition temperature for luminous characteristics was about 500~ in this investigation. A blue cathodoluminescent emission peaked at 470 nm was observed. Good luminescent properties were observed in the films which exhibit the standard ZnGa204 x-ray diffraction pattern. Field emission display (FED) is a new kind of vacuum flat cathode ray tube. Due to the attractive advantage of FED, it is a good candidate for replacing conventional cathode ray tube (CRT) in flat panel display. In FED, light emission is based on low voltage cathodoluminescence. 1'2 Usually, phosphors show a decrease in cathodoluminescent efficiency as the accelerating voltage is reduced, especially below 1 kV. Low-voltage (of the order of 50 V) CL phosphors have also attracted substantial interests for the reduction in accelerating voltage in cathode tubes. 35 The ZnGa204 phosphor has been investigated for its good cathodoluminescence characteristics at low voltage. A minous efficiency of 0.7 im/W has been obtained when this phosphor is operated at 30 V dc. The results of high temperature operating lifetime test have been proven to show the excellent stability of this phosphor. In addition, ZnGa2Q shows emission from green to red when it is doped with Cr and IV[n, and also shows blue emission even without being doped with impurity. The conventional phosphors have been prepared by powder metallurgy. In the recent development, the thin films of ZnGa204 phosphor were of interest for the applications of FED. The properties of phosphors are strongly dependent on the particle size and crystal structure, 6'7 and the growth conditions may be adjusted to achieve better luminescent characteristics. In this work, the technique of sputtering was employed to deposit ZnGa204 phosphor films. The sputtering condition were adjusted for investigating the relationship among deposition condition, deposition rate, and luminescent characteristics.