Broad band emission behaviors in ZnS thin film electroluminescent devices

Time-resolved emission spectra and transient emission behavior at various wavelength regions were measured for doubly insulated thin-film electroluminescent devices having electron-beam-evaporated undoped ZnS or ZnS:TbFx as the active layer under an alternating pulse voltage of 500 ns width. The broad-band emission intrinsic to the ZnS host was observed in the wavelength region from 320 nm to 700 nm, and this emission showed a maximum at 250 ns and then decreased quickly regardless of the wavelength. The emission of Tb3+ ion appeared with the decay of the broad-band emission and was saturated within an applied pulse width.