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Trailing edge phenomena in SrS:CeCl3 thin film electroluminescent devices

: Troppenz, U.; Hüttl, B.; Velthaus, K.O.; Mauch, R.H.


Journal of Crystal Growth 138 (1994), No.1-4, pp.1017-1022
ISSN: 0022-0248
International Conference on II-VI Compounds and Related Optoelectronic Materials <6, 1993, Newport, Ri.>
Conference Paper, Journal Article
Fraunhofer HHI ()
cerium compounds; charge transfer states; electroluminescent displays; luminescence of inorganic solids; luminescent devices; optical films; photoluminescence; radiation quenching; spectral line intensity; strontium compounds; thin film devices; time dependence; thin film electroluminescent devices; multilayer structures; voltage dependent photoluminescence; laser excitation; ce3+ ions; photo-induced transferred charge; photo-induced electroluminescence; pel; voltage levels; el threshold; trailing edge; voltage pulse; pl intensity; applied voltage; quenched pl; mean electric field strength; weakly accelerated electrons; srs:cecl3

SrS:CeCl3 based thin film electroluminescent devices in conventional and multilayer structures have been investigated by means of time and voltage dependent photoluminescence (PL) measurements after laser excitation of the Ce3+ ions. It turned out that a significant photo-induced transferred charge as well as photo-induced electroluminescence (PEL) occurs at voltage levels far below the actual EL threshold, mainly in the trailing edge of the voltage pulse. Furthermore, a reduction of the PL intensity by increasing the applied voltage is observed. At EL threshold voltage, the PL intensity is as low as 65-75% of the zero voltage value. These observations are independent of the device structure. The PEL can be described as a partial regain of the quenched PL, being more pronounced in the multilayer case due to a higher mean electric field strength in the SrS:CeCl3 layers. To explain the experimental findings, a quenching caused by weakly accelerated electrons is proposed.