Luminance Improvement of Red‐Emitting CaS : Eu Thin film Electroluminescent Cells Prepared by Electron Beam Evaporation

Abstract

Luminance of red‐emitting thin‐film electroluminescent (TFEL) cells was improved by increasing deposition rate through control of the electron beam current. Crystallinity and cathodoluminescence characteristics were investigated. Crystallinity was improved by increasing the deposition rate or the surface temperature of the evaporation sources; both the grain size and the fraction of the grains with the (111) direction normal to the substrate surface were increased. From the cathodoluminescence study it was suggested that with increase of the deposition rate the distribution of Eu²⁺ions became more uniform, causing an increase in luminance.