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 Y₂O_3-xS_x 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.