衬底温度对CaS∶TbF_3薄膜电致发光亮度的影响

EFFECT OF THE SUBSTRATE TEMPERATURE ON BRIGHTNESS OF CaS∶TbF 3 ELECTROLUMINESCENT THIN FILMS

利用Ｘ射线衍射和扫描电子显微镜对不同衬底温度下电子束蒸发的ＣａＳ∶ＴｂＦ３电致发光薄膜的结晶性和表面形貌进行了研究．通过对薄膜的透射率和漫反射率的测量研究了薄膜的致密性．Ｘ射线衍射表明衬底温度在２２０到５８０℃范围之间，电子束蒸发的ＣａＳ∶ＴｂＦ３电致发光薄膜为多晶立方晶相．随着衬底温度的提高，ＣａＳ∶ＴｂＦ３薄膜的表面形貌发生显著的变化，薄膜的致密性增加，从而增加了电致发光亮度．

The crystallinity and morphology of crystalline grains were studied on CaS∶TbF 3 electroluminescent thin films prepared by electron beam evaporation under different substrate temperatures from 220 to 580℃. The brightness of the electroluminescence strongly increased with increasing the substrate temperatures. X ray diffraction analysis indicated that the CaS∶TbF 3 films were polycrystalline with cubic phase. The surface morphology of the films, the decrease of the diffuse reflectance and the increase of transmittance indicated that the CaS∶TbF 3 films became denser with increasing the substrate temperatures. These changes reduce scattering to hot electrons and finally caused a strong increase of the electroluminescent brightness by increasing hot electrons energy in CaS∶TbF 3 films.