An investigation of the electrical and optical properties of DC electroluminescent ZnS:Mn, Cu-powder panels

Electrical and optical measurements on ZnS : Mn, Cu-dc electroluminescent (DCEL) powder panels are reported. It is shown that current conduction in these devices depends upon avalanche breakdown in a thin insulating Cu-depleted layer of phosphor of thickness up to approximately 1 µm. However, it is concluded that the overall current-voltage characteristics of a panel are determined by the various components external to this layer. That the current density throughout this layer is highly nonuniform is deduced and the consequences of this result are discussed in terms of the effect on saturation brightness. A new model to explain the details of the observed electrical behavior of DCEL powder panels is introduced and compared with previously proposed models. Finally the various failure modes observed in these devices are identified and their elimination is discussed.