TRANSIENT EMISSION MECHANISMS IN THIN-FILM ELECTROLUMINESCENT DEVICESWITH RARE-EARTH-ION-ACTIVATED SRS PHOSPHOR LAYERS

Transient emission processes in rare-earth-ion-activated SrS thin-film electroluminescent (TFEL) devices have been investigated by measuring emitted light waveforms. The rare-earth-ion activators are Ce3+, Pr3, Nd3+, Eu3+, Sm3+, Tb3+, Dy3+, Er3+, Ho3+ and Tm3-. The waveforms can be classified into three groups according to ;light emission responsi bility (LER) to applied voltage pulse. In Group 1, Tb and Dy with slow LER show abrupt decay at the trailing edge of each driving voltage pu lse. This is due to the Auger process with strong interaction of the e xcited ions with electrons flowing backward in the SrS conduction band . In Group 2, Ce, Pr, Nd, and Eu with fast LER cause secondary emissio n at the edge. In Group 3, other; ions show slower LER than in Group 2 , in particular, Er decay curves indicate a single luminous center.