Electroluminescence of ZnS: Mn, Cu, Cl Films

Abstract

In sandwich and gap cells of ZnS: Mn, Cu, Cl films, the emitting portion of electroluminescence under ac and dc excitation was investigated by microscopic observation. The relation between the brightness and the polarity of applied voltage was also examined. In the case of ac excitation, overlap of emitting layer was observed in sandwich cell, while in gap cell the emission originated from various portions such as along the both electrodes, along some deposit or at spots distributed throughout the gap. In the case of dc excitation in the sandwich cell, the emission was stronger and more homogeneous under the positive metal electrode than under the negative one. The emission in gap cell under dc excitation always originated from the anode. Current-voltage characteristics of films have no direct connections with brightness. From these results, it seems that dc electroluminescence of ZnS: Mn, Cu, Cl films is excited by the hole injection from the Cu-rich phase to the ZnS phase.