稀土离子掺杂的铝酸锌膜的低压阴极射线发光

Low Voltage Cathodoluminescence of Rare-earth-doped Zinc Aluminate Films

在空气中采用喷雾热解法合成了稀土铕(Eu)、铽(Tb)及铥(Tm)掺杂的铝酸锌(ZnAl_2O_4)发光膜,研究了合成条件对其阴极射线发光特性的影响。ZnAl_2O_4:Tb^(31)、ZnAl_2O_4:Tm^(3+)及ZnAl_2O_4:Eu^(31)膜分别发出主峰位于555 nm的绿光、主峰位于478 nm的蓝光及主峰位于616 nm的红光。上述发光均可在低退火温度(700℃以下)下获得,因此可以使用玻璃作为基底。同时研究了样品发光的色坐标和色纯度,并与标准的红、绿、蓝粉的色品度进行了比较。样品的亮度和效率都随外加电压的增加而增大,没有观察到亮度饱和现象。此外,Eu掺杂的ZnAl_2O_4膜在850℃以上、还原气氛中退火后呈现Eu^(2+)的特征发射——宽的蓝发射带。

Field emission display （FED） technology has been actively investigated with regard to use in full color flat panel displays. This technology requires that a phosphor screen is developed to operate under a lower electron accelerating voltage, typically 1 ~ 5 kV, than a conventional cathode ray tube （CRT） screen. The conventional red-green-blue （RGB） phosphors for cathode-ray tubes （CRT） are not applicable to field-emission displays （FEDs） because they need high efficiency at low excitation voltage, a high resistance to current saturation, a high chemical and thermal stability, and long lifetime at high current density. Furthermore, it is difficult to find a suitable blue phosphor. There is, therefore, a need to develop new phosphors that display a higher efficiency than the materials conventionally used in CRT screens while operating under low to medium electron accelerating voltages. There is considerable interest in the development of rare-earth-doped oxide-based phosphors for FEDs because of their excellent light output, color rendering properties, and superior stability under electron bombardment. In this paper, polycrystalline undoped and Eu-, Tb-, and Tm- doped zinc aluminate （ZnAl2O4） thin film phosphors were prepared by the spray pyrolysis technique at ambient pressure and the optical absorption and the effects of preparation conditions on the cathodoluminescence properties of the films were studied, Films containing Tb^3＋ and Tm^3＋ ions exhibited green and blue cathodoluminescence, respectively. For films doped with europium, both red emission lines from Eu^3＋ and a broad blue-green emission band from Eu2＋ were observed. The CIE chromaticity coordinates, dominant wavelength, and color purity were determined for each phosphor. The CL luminance and efficiency of each phosphor at a current density of 57 μA/cm^2 depended linearly on the excitation voltage.