CRT phosphors and application to FED phosphors

Discussion is focused on the issue of efficiency among many requirements imposed on cathode‐ray phosphors to meet the demands for high‐definition television and high‐resolution monitor tubes. Basic studies are encouraged to predict the limit of efficiency more precisely. The results of recent research on luminance saturation and efficiency degradation under intense electron‐beam irradiation are reviewed. These problems are more serious in FEDs than in CRTs because of the high current density in FEDs. The important role of the electrical charging in limiting the efficiency is stressed by looking back to a published result that a clean CdS surface, on which a low‐work‐function material is deposited, can be excited by 20‐eV electrons. Introduction of elements with mixed valences into oxides is proposed to increase the concentration of oxygen vacancies and consequently the electrical conductivity. It is, however, expected that there will be a tradeoff relationship between the electrical conductivity and luminance saturation due to Auger processes.