Luminescent Properties of CaS : Cu, F TFEL Devices on Si Substrate

Abstract

CaS : Cu, F thin-films have been prepared with the aim of development a blue-emitting thin-film electroluminescence (TFEL) device with high luminance and good chromaticity. The dependence of structural and photo-luminescent (PL) properties of CaS : Cu, F thin-films prepared by electron beam on annealing temperature and time after the deposition was investigated. Crystallinity and PL intensity of the films were improved significantly by annealing at temperatures higher than 800°C for up to 10 min. The improvement showed a tendency toward saturation for annealing at longer than 10 min. The above results indicate that annealing for around 10 min is suitable. The CaS : Cu, F TFEL device was fabricated on an Si substrate using SiO₂ and Y₂O₃ films as insulator layers, and ZnS films as buffer layers. The device annealed at 850°C for 10 min with 0.3 at% of Cu⁺ was obtained a blue emission with an obvious peak of 425 nm, CIE coordinates of x=0.217, y=0.223.