Emission Centres in Indium-Activated Zinc Sulphide Crystals

Abstract

Indium-activated zinc sulphide single crystals were investigated on their luminescent, photoconductive and optical properties. Fairly bright yellow and green emissions were observed under ultraviolet excitation. Besides, additive coloration was found in ultraviolet and visible regions. The relative intensities of yellow and green emissions were strongly dependent on the stoichiometric composition of the crystals. The yellow emission was found to be closely correlated with the additive coloration and the photoconductivity. On the other hand the green emission was found to have less relation with the additive coloration and the photoconduction. Models were proposed for both emission centers based on the dual character of the indium ion: a trivalent indium ion in zinc site is the yellow emission center and a monovalent indium ion is the green emission centre.