Europium doping induced symmetry deviation and its impact on the second harmonic generation of doped ZnO nanowires

In this work, we investigated the effects of europium doping on the second harmonic generation (SHG) of ZnO nanowires (NWs). A non-monotonic enhancement in the SHG is observed with the increase of the europium concentration. Maximum SHG is observed from the 1 at.% europium doped ZnO NWs with an enhancement factor of 4.5. To understand the underlying mechanism, the effective second order non–linear coefficient (d eff ) is calculated from the theoretical fitting with consideration of the absorption effect. Microstructural characterization reveals the structural deformation of the ZnO NWs caused by europium doping. We estimated the deviation in the crystal site symmetry around the Eu 3+ ions (defined as the asymmetric factor) from photoluminescence measurement and it is found to be strongly correlated with the calculated d eff value. A strong linear dependence between the magnitudes of d eff and the asymmetric factor suggests that deviation in ...



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