Evidence for recombination-controlled electroluminescence in alkaline-earth sulfides

Thin-film alkaline-earth-sulfide electroluminescent devices exhibit, under voltage-step excitation, an unexpected decrease in the light output if the voltage is abruptly increased at some time after the beginning of the step. We use this phenomenon to demonstrate that the dynamics of the light emission is controlled by field-dependent trapping and eventual recombination at empty activators rather than impact excitation of activators.