Effects of ytterbium doping on the ultraviolet emissions of MgZnO films prepared by magnetron sputtering

In this work, we studied the effects of rare earth ytterbium (Yb) doping on the structure and ultraviolet (UV) emission properties of MgZnO films deposited by magnetron sputtering and subsequent high-temperature annealing. For the samples with low and medium Mg content, the UV photoluminescence (PL) and cathodoluminescence (CL) increased considerably by the Yb doping, while for the samples with higher Mg content they decreased. X-ray diffraction indicates the formation of MgZnO nanocrystals in the samples, together with the formation of Mg- and Zn- silicates, as well as the formation of Yb silicates and Yb2O3 after the Yb doping. The surface morphologies of the samples are sensitive to the Mg content and the Yb doping level as observed by scanning electron microscopy. The UV-visible absorption spectra show that the optical bandgap of the samples with medium/or higher Mg content, both increase slightly by the Yb doping. The PL decay spectra indicate that the lifetime of the UV PL increases with Yb doping for the samples with low content of Mg, while decreases for the samples with high Mg content. The results demonstrate that UV emissions are closely related to the film quality after the Yb doping. This work may be useful to broaden the UV emission of ZnO-based materials in the UV photonics.