Infrared quenching of electroluminescence in ZnS: Mn thin-film electroluminescent structures

Electroluminescence from thin-film electroluminescent devices is found to be quenched after IR irradiation of the devices in the interval between exciting voltage pulses. The IR irradiation decreases the emission intensity in the spectral range 530–540 nm, while increasing it between 640 and 690 nm. These effects are explained by IR-induced charge exchange between the deep centers due to V _S ²⁺ and V _S ⁺ sulfur vacancies, an increase in the concentration of the latter vacancies, and the redistribution of the channels of impact excitation of Mn²⁺ and V _S ⁺ centers in favor of V _S ⁺ centers. The cross section and rate of impact excitation of V _S ⁺ centers, the photoexcitation cross section for V _S ²⁺ centers, the IR radiation absorption coefficient, the internal quantum efficiency of electroluminescence, and the probability of radiative relaxation of Mn²⁺ centers, as well as the electron multiplication factor in the phosphor layer, are evaluated.