Abstract: Based on the structure of ceramic substrate/internal electrodes/thick dielectric film/light-emitting layer/thin dielectric film/ITO,the fabrication process of ZnS:Mn phosphor layer has been investigated to improve the brightness of inorganic thick dielectric electroluminescent(TDEL) devices.The optimal thickness and fabrication temperature of ZnS∶Mn film are 600?nm and 280?℃,respectively,and produced the highest brightness of TDEL devices.The photoelectric properties of TDEL devices were improved by an annealing process of ZnS∶Mn layer,and the optimal brightness-voltage curve(that is,the biggest brightness and the steepest curve) of TDEL devices was obtained by an annealing temperature of 500?℃.The improvement of photoelectric properties of TDEL devices by the optimal fabrication temperature and annealing temperature of ZnS∶Mn layer was attributed to the crystalline improvement of ZnS∶Mn layer and the uniform diffusion of Mn+.