Concentration quenching in Eu-doped ZnO grown by sputtering-assisted metalorganic chemical vapor deposition

The dependence of Eu3+ photoluminescence (PL) properties on Eu concentration was studied in Eu-doped ZnO (ZnO:Eu) thin films grown by sputtering-assisted metalorganic chemical vapor deposition (SA-MOCVD). The ZnO:Eu showed band-edge PL from ZnO and red emission lines due to the intra-4f transitions in Eu3+ ions at room temperature (RT). The intensities of band-edge and Eu3+ PL decreased with the increasing Eu concentration. In the temperature dependence of Eu3+ PL, the ZnO:Eu with high Eu concentration showed large thermal quenching of the PL intensity. In addition, the lifetimes of Eu3+ PL became short at high Eu concentration. The concentration quenching mechanism of Eu3+ PL using a model based on non-radiative recombination processes in ZnO and Eu3+ ions was presented.