Electroluminescence in zinc sulpho-selenide and in zinc sulphide

Abstract

Light-emitting devices with electrode areas of 1 mm² have been prepared on single crystals of solid solutions of zinc selenide and zinc sulphide. It is shown that it is relatively easy to prepare ohmic contacts with indium on samples containing lp to 80% molar of sulphur. The most intense electroluminescence has been obtained from devices carrying one indium and one evaporated gold electrode. With samples with compositions ranging from ZnSe to ZnS_0.8Se_0.2 the more intense luminescence is emitted in reverse bias (gold negative), whereas with samples with higher sulphur concentrations a higher luminance is achieved in forward bias. The colour of the emission was blue with a maximum intensity at 4700 AA. The addition of as little as 2% selenium was sufficient to change the visual effect to green. With ZnSe the luminescence was yellowish-red.