Emission characteristics, crystalline phase and composition of Er3+/Yb3+ doped LiNbO3 thin films deposited by e-beam evaporation

Er3+/Yb3+ doped LiNbO3 (LN) single crystal films with varying Yb3+ doping level were grown on z-cut LiTaO3 bulk single crystals via using e-beam evaporation method. The crystallographic orientation, elemental distribution, fluorescence properties, ionic valence states, Er3+ concentration, Yb3+ concentration and Li2O content of films were carefully studied. Results from XRD, SEM and Raman scattering conclude that the predominant phase of these films is LN and they are oriented along (006). The results of energy dispersive spectroscopy indicate that constituent elements are uniformly distributed over the entirety of the films. The visible and near-infrared luminescence intensities rise with increasing Yb3+-doping concentration. The Li2O content of films remains constant at 48.8 mol% with growing Yb3+-doping level based on the optical birefringence method, which is consistent with the Raman results. XPS results suggest that the Er3+ and Yb3+ concentrations in the films are lower than that in the polycrystalline powder since e-beam evaporation has a low efficiency of heavy Er3+ and Yb3+ ions.