Bulk photovoltaic effects in Mn-doped BiFeO^sub 3^ thin films and the optical strains

Pt/1-µm-thick Bi1.0Fe0.99Mn0.01O3 (BFMO)/Pt coplanar capacitors with an interelectrode distance of 260 µm have been fabricated on vicinal SrTiO3 (STO) (001) substrates by radio frequency magnetron sputtering. The bulk photovoltaic effect of a BFMO thin film has been investigated by measuring the current–voltage (I–V) characteristics of the Pt/BFMO/Pt coplanar capacitors under blue-violet laser illumination (λ = 405 nm). The I–V characteristics show the light-polarization-dependent open-circuit voltage (V OC) with a maximum of −209 V. In addition, the optical strain of a BFMO/STO cantilever with a size of 15 mm × 1.3 mm × 70 µm has been investigated by measuring the displacement of the edge of the cantilever under blue-violet laser illumination. The edge displacement depended on light polarization, indicating that the optical strain is due to the coupling between the bulk photovoltaic effect and the inverse piezoelectric effect.