Formation and optical characteristics of ZnO:Eu/ZnO nanowires grown by sputtering-assisted metalorganic chemical vapor deposition

Abstract We report on the growth and optical characteristics of Eu-doped ZnO (ZnO:Eu) films on ZnO nanowires (NWs) by sputtering-assisted metalorganic chemical vapor deposition. ZnO:Eu films are grown by sputtering Eu 2 O 3 targets during the growth of ZnO NWs. The crystal quality of ZnO host materials is improved by using the NW configuration due to a strain relaxation effect, which is elucidated by optical characterization. An enhancement of Eu 3+ luminescence at 613 nm is observed at room temperature for the ZnO:Eu/ZnO NWs as compared to a conventional film. Site-selective spectroscopy by direct excitation of Eu 3+ ions by a tunable dye laser reveals that the most intense emission peak is located at a wavelength of ∼613.5 nm, which coincides with the main peak under indirect excitation. This result indicates that the observed enhanced Eu luminescence is due to a relative increase in the number of Eu centers which can effectively be excited via the host material.