Ferroelectric photovoltaic materials have been subjected to intensive research in view of their applications for high-performance self-biased UV photodetectors. This work reports the ferroelectric polarization-enhanced near-UV (λ = 405 nm) and UVA (λ = 360 nm) photoresponse of the indium-tin-oxide (ITO)/(Bi_0.93Sm_0.07)FeO₃/Pt and ITO/(Bi_0.93Gd_0.07)FeO₃/Pt heterostructures. A superior photoresponse was observed in the ITO/(Bi_0.93Gd_0.07)FeO₃/Pt device with photoresponsivity of ∼7.3×10−2A/W, specific detectivity of ∼2.5×1011Jones, and response times of �� ∼1 ms and �� ∼1 s under 360-nm light illumination. The photocurrent generation is facilitated by the interfacial E fields and ferroelectric polarization-induced E field. The improved photosensing ability is ascribed to the collective effect of the electric field-enhanced interaction between oxygen 2p and Fe 3d orbitals and the interconnection of grain boundaries and domain walls that plays roles of charge transport paths. (Bi_0.93Gd_0.07)FeO₃ exhibited a more superior photoresponse than (Bi_0.93Sm_0.07)FeO₃ due to its more complex domain structure, smaller bandgap, and stronger orbital hybridization. These results demonstrate the feasibility of utilizing the ferroelectric polarization and domain structure in (Bi_0.93Gd_0.07)FeO₃ to enhance photodetection, thus providing a route for the realization of a highly sensitive and self-biased visible-UVA photodetector.[Link to this article...]

Keywords: Heterostructure Photoresponsivity Specific detectivity Photoconductive gain Response time Domain wall