ELECTROLUMINESCENCE FROM CAS-TMF3 FILM PREPARED BY RADIO-FREQUENCY MAGNETRON SPUTTERING

Blue electroluminescence is reported from CaS:TmF3 thin films prepared by radio frequency magnetron sputtering method. The dependences of br ightness on substrate temperature, concentration of TmF3, and the appl ied voltage were investigated on alternating current thin-film electro luminescent devices. The obtained maximum brightness was above the lev el of ZnS:TmF3 devices. The equivalent average energy of the excited e lectrons contributed to the electroluminescence in CaS:TmF3 alternatin g current thin-film electroluminescent devices and was estimated at ar ound 4.23 eV by comparing the ratio of infrared to blue peak in electr oluminescent spectra with that in photoluminescent spectra excited by different photon energy. The excitation processes of electroluminescen ce in CaS:TmF3 thin films were assumed to be energy transfers from the conduction band edge to Tm3+ centers. (C) 1998 American Institute of Physics.