Energy levels of defects in electroluminescent ZnS : Mn thin films exhibiting hysteresis and self-organized patterns

Two characterization methods (photodepolarization spectroscopy and the volt age dependence of the transferred charge) have been used to study the energ y depth of defect states in ZnS : Mn electroluminescent structures showing a hysteresis in the charge-voltage and luminance-voltage characteristics. T he hysteresis effects are accompanied by the formation of self-organized pa tterns. We show that there is a correlation between the concentration and t he energy depth of the defects in the film, on the one hand, and the hyster esis width as well as the patterns observed, on the other hand. The influen ce of defect states on the hysteresis and self-organization phenomena is di scussed. (C) 2000 Elsevier Science B.V. All rights reserved.