Electroluminescence of Devices with Thin-Film CaS:Ce3+, Cl- as the Active Luminescent Layer

Thin-film CaS:Ce3+, Cl- has been successfully employed for the first time as the active layer of an a.c. thin-film electroluminescent device. In order to compare the performance of a device using this material with that of devices employing the usual ZnS:Mn2+ material, MISM (metal-insulator-semiconductor-metal), ISM, and MSM devices were fabricated. Of these three devices, the singly-insulated device had the highest brightness, of 100 cd/m2, at a frequency of 5 kHz and a pulse height of 200 V. The brightness of this device is still lower than that of devices employing the usual ZnS:Mn2+. This is attributed to the smaller number of internal carriers and the smaller amount of carrier accumulation in the vicinity of the interface between the active luminescent layer and the insulating layer.