Electroluminescence in Calcium Sulphide

Abstract

Interest in alkaline earth II–VI chalcogenides has been stimulated by the extended range of band gaps available compared to that of conventional II–VI compounds. LEHMANN [1], in reviewing the luminescence characteristics of calcium sulphide, drew out the versatility of this compound in its capacity to accept a wide range of dopants, including the rare earth elements, which could emit in different segments of the visible spectral range. Much of the early interest in calcium sulphide was centred on its cathodoluminescent characteristics and these have been exploited recently in the commercial context as CaS_1–xSe_x photocathodes in cathode ray tubes. Fluorescence and thermoluminescence are other characteristics that have been explored in colour controlled emitters and dosimeters respectively; the latter application has been developed to some degree using CaS.