Influence of sintering on photoluminiscent emission of SrS:Cu,Ag powders and e-beam evaporated phosphor layers

Recently, SrS:Cu,Ag has been studied by several research groups as a blue emitter for thin film electroluminescent (EL) devices. However, both EL and PL (photoluminescent) spectra of these thin film phosphors suffer from severe non-reproducibility. In order to solve this problem, the effect of sintering the deposition source material (in N2 and H2S) on the PL characteristics of both this source material and the deposited thin films is studied. It will be shown that sintering SrS:Cu,Ag in H2S enhances blue Ag emission in thin films, which is normally partly quenched at room temperature. Sintering also drastically increases the reproducibility of the emission spectra. In order to understand the underlying physical changes, optical and structural/morphological characterizations were performed.