Domain-wall photovoltaic effect in Fe-doped BaTiO3 single crystals

A single crystal of Fe (0.3%)-doped BaTiO3 was grown by a top-seeded solution growth method, and the photovoltaic (PV) properties (at 3.1 eV) in a multi-domain state with a 90° domain structure are investigated. We show that the overall behavior can be well understood by an analytical expression of the domain wall (DW)-PV effect superimposed on the bulk-PV effect. The fitting of photocurrents as a function of light polarization reveals that the offset component of the DW-PV effect is much larger than that of the bulk-PV effect, even though the volume fraction of the DW region is extremely small. A local electric field in the DW region is estimated to be several hundred kV cm−1, which is three orders of magnitude higher than the effective field inside the domains.