Erasing characteristics of a thin-film electroluminescent ZnS:Mn faceplate

Experimental results show that it is not possible to erase completely electroluminescent ZnS:Mn memory device biased near the threshold voltage, for erase time pause of the order of tens of milliseconds, by either the "bulk" erase or the "selective electron beam" erase method. The selective erase requires a time delay before reimposition of the normal sustain voltage to allow a significant decay of persistent beam-induced conductivity. The process of bulk erasure can be explained satisfactorily by a theoretical model which treats the macroscopic electroluminescent region as an ensemble of bistable microscopic filaments, with each filament having a field-dependent coefficient for the recombination of the deep hole traps with the electron flux. The simple assumption of a Gaussian distribution of extinction voltages for the ensemble of microscopic filaments is sufficient to explain the experimental results, except near the threshold voltage where the measured curves show oscillatory features which remain unexplained.