Abstract
We studied the photoluminescence (PL) properties of (Ce + Yb) co-doped ZnO thin films as a function of high temperature annealing. The films were fabricated by magnetron sputtering. After 1000-1100°C annealing, the near band edge (NBE) emissions of the films were dozens to a hundred times stronger than that of undoped ZnO, while the Yb3+ emission (~980 nm) was quite weak, indicating that energy transfers from the ZnO host to Yb3+ ions in the films were not efficient. X-ray diffraction analysis and scanning electron microscopy observations demonstrated that the (Ce + Yb) co-doping had a large effect on the morphology and crystallinity of the films. The crystallinity enhancement of the films is considered to be the main reason for the strong NBE enhancements of the co-doped ZnO films.
Highlights
There are several reviews on the applications of rare earth elements (REs) in various host materials used for optical applications such as upconversion of photons, color conversion or thermometry [1,2,3]
Luo et al [18] reported that strong UV lasing occurred in their Eu doped ZnO films, where Eu2O3 precipitated on the surface of the ZnO host
In conclusion, we have reported that after 1000-1100 °C annealing, the near band edge (NBE) emissions of (Ce, Yb) co-doped ZnO films were dozens to hundred times stronger than that of undoped ZnO, while the Yb3+ emission (~980 nm) was quite weak indicating that energy transfer from the ZnO host to Yb3+ ions in the films were not efficient
Summary
There are several reviews on the applications of rare earth elements (REs) in various host materials used for optical applications such as upconversion of photons, color conversion or thermometry [1,2,3]. Ce3+ can emit blue light and the absorption cross section of the electric-dipole allowed 4f-5d transition is large (of the order of 10−18 cm2), while the radiation from Yb3+ (~980 nm) has many important applications. We reported that after high temperature (1000-1100 °C) annealing, the NBE emissions of ZnO films were both enhanced by one to two orders of magnitude after doping with Ce [19] or Yb [20] compared to the undoped case, whereas the structures of the two films were quite different. The strong NBE emissions from the RE doped ZnO may pave a way to develop ZnO UV based photoelectric devices
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