Pulsed KrF laser annealing of ZnS : Mn laterally emitting thin film electroluminescent displays

Pulsed KrF (248-nm) laser annealing was investigated as a post-deposition p rocess for RF sputtered ZnS:Mn phosphor layers used in laterally emitting t hin film electroluminescent (LETFEL) displays. LETFEL devices consist of a phosphor layer sandwiched between two insulating thin films (Y2O3), grown o nto silicon substrates patterned with micro-mirrors (SiO2). The micro mirro r structure permits surface viewing by reflecting laterally emitted light d ue to internal waveguiding effects. Laser irradiation of the uncoated phosp hor layer was performed using KrF excimer 248-nm laser pulses of 20 ns unde r an argon overpressure of 10.34 bars to limit laser ablation. The influenc e of the laser irradiation fluence on the LETFEL performance was investigat ed from 0.3 to 1.5 J/cm(2). In this paper, we have reported the brightness- voltage characteristics of laser annealed, non-annealed and thermally annea led devices at 500 degreesC for similar to 1 h. It is shown that the onset for light emission (threshold voltage) decreases with laser annealing. Usin g this novel method of annealing, the brightness of LETFEL devices is obser ved to increase with increasing laser fluence. (C) 2001 Elsevier Science B. V. All rights reserved.