Control of Eu Oxidation State in Y₂O_3−xS_x:Eu Thin-Film Phosphors Prepared by Atomic Layer Deposition: A Structural and Photoluminescence Study

Structural and photoluminescence studies were carried out on Eu-doped Y2O3−xSx thin films grown by atomic layer deposition at 300 °C. (CH3Cp)3Y, H2O, and H2S were used as yttrium, oxygen, and sulfur precursors, respectively, while Eu(thd)3 was used as the europium precursor. The Eu oxidation state was controlled during the growth process by following the Eu(thd)3 pulse with either a H2S or O3 pulse. The Eu(thd)3/O3 pulse sequence led to photoluminescence emission above 550 nm, whereas the Eu(thd)3/H2S pulse sequence resulted in emission below 500 nm.