Influence of high temperature annealing of each interface of red-emitting CaS : Eu TFEL devices

Abstract

Red-emitting CaS : Eu thin film electroluminescence (TFEL) devices were fabricated on Si substrates by the electron beam evaporation and its luminescent properties were investigated. PL spectrum of CaS : Eu phosphor was measured under excitation with 325nm of He-Cd laser at room temperature. It was shown that PL spectrum, where concentration of Eu was 1.0 at%, showed strong red emission with a peak at about 650nm. Standard double insulator structure was employed for EL device fabrication using SiO_2 and Y_2O_3 films as insulating layers. The TFEL devices prepared with annealing at 800℃ for 15min in H_2S showed the same red emission as PL spectrum. At the same time, CIE color coordinates x=0.67, y=0.32 could be obtained from the device with a Eu content of 1.0 at%.