Improved blue luminescence in Ag-codoped SrS:Ce thin films made by atomic layer epitaxy and ion implantation

Silver ions were implanted into SrS:Ce3+ thin films grown by atomic layer epitaxy (ALE) to examine the effects of Ag+ codoping on the luminescence of SrS:Ce3+ used in thin-film electroluminescent (TFEL) devices. High-temperature annealing (800 °C) of the standard ALE SrS:Ce prepared at 510 °C caused a pronounced blueshift of the photoluminescence (PL) emission, but the intensity was decreased. Codoping by ion implantation of Ag+ and high-temperature annealing (800 °C) caused no further blueshift but the PL intensity was more than double that of the nonimplanted samples. The implanted SrS:Ce, Ag also exhibited the longest decay value (SN=22 ns at 520 nm with 420 nm excitation) reported for ALE SrS:Ce thin films. The improved PL properties show that codoping with Ag+ can be advantageous in ALE SrS:Ce3+ thin films used for electroluminescent multicolor and full-color flat panel displays. The results also suggest the potential of the ion implantation technique in TFEL device preparation.