Photovoltaic properties in an orthorhombic Fe doped KTN single crystal

Since the domain wall photovoltaic effect (DW-PVE) is reported in BiFeO₃ film, the investigations on photovoltaic properties in ferroelectrics have appealed more and more attention. In this work, we employed two Fe doped KTa_1-xNbxO₃ (Fe:KTN) single crystals in tetragonal phase and orthorhombic phase, respectively, possessing similar net polarization along [001]_C direction, to quantize the contribution on photovoltaic properties from bulk photovoltaic effect (BPVE) and DW-PVE in Fe:KTN. The results show that there are significant enhancements of open-circuit voltages (V_OC = -6.0 V, increases over 440%) and short-circuit current density (J_SC = 18.5 nA cm^-2, increases over 1580%) in orthorhombic Fe:KTN with engineer-domain structure after poled, corresponding to 14.2 mV and 2.2 mV for the single domain wall and bulk region under illumination of 405 nm light (100 mW). It reveals that DW-PVE plays a major role in KTN-based ferroelectrics, indicating an orthorhombic Fe:KTN single crystal is one of the potential photovoltaic materials.