Electroluminescent Devices With CaS:Eu²⁺ Active Layer Grown by R.F. Reactive Sputtering

Abstract

Over the past few years, intensive work has been made to achieve color thin film electroluminescent (E.L.) devices. Alkaline-earth sulphide CaS and SrS are the most promising materials for red and blue colors [1, 2, 3 ]. Nowadays, the active layer CaS:Eu²⁺ is the material of choice which emits the fundamental red color. This layer is usually grown by electron-beam evaporation [ 2, 3 ] but it is necessary to heat the substrate up to a 680°C temperature, which leads to technological difficulties. R.F. reactive sputtering technology can overcome these problems [ 4,5 ]. We report here on the optimization of growth conditions for CaS:Eu²⁺ thin films by this technique. We also report the results obtained when this active layer is integrated in E.L. devices.