RELAXATION OF PHOSPHOR FIELD IN SRS-CE THIN-FILM ELECTROLUMINESCENT DEVICES

Capacitance-applied voltage and internal charge-phosphor field characteristics of SrS:Ce thin film electroluminescent devices have been studied. The average phosphor field of the SrS:Ce films reaches the maximum of 1.3 MV/cm and relaxes to 0.7 MV/cm, although the applied voltage increases. The turn-on voltage of the SrS:Ce thin film electroluminescent device decreases nonlinearly with increase of conduction charge and depends on the slew rate dV/dt. A large spike current is observed and is thought to correspond to the charge generation in the SrS:Ce layer, which results in the space charge, and causes a relaxation of phosphor field in the SrS:Ce films.