INFLUENCE OF ULTRAVIOLET-IRRADIATION ON EXCITATION EFFICIENCY AND SPACE-CHARGE IN ZNS THIN-FILM ELECTROLUMINESCENT DEVICES

Alternating current driven ZnS thin-film electroluminescent devices (A CTFELDs) have been investigated under continuous-wave ultraviolet (UV) irradiation. Under specific experimental conditions, UV irradiation c an erase the residual polarization between two electric pulses which i s caused by stored charges in the semiconductor and the semiconductor- insulator interfaces. No photodielectric effects have been observed. T he reduction of the residual polarization allows one to investigate th e role of the space charge in ACTFELDs, by comparing the excitation ef ficiencies with and without UV irradiation.