Bulk photovoltaic effect in a BiFeO₃thin film on a SrTiO₃substrate

Abstract

Epitaxial BiFeO3 (BFO) thin films with striped- and single-domain structures have been grown on SrTiO3 (STO) (103) and (113) substrates by radio-frequency planar magnetron sputtering. The domain structure of BFO was controlled by the orientation of the STO substrate. Piezoelectric force microscopy revealed that BFO thin films on STO (103) and STO (113) had a striped-domain structure with 71° domain walls running along 〈010〉STO, and a single-domain structure, respectively. To confirm the photovoltaic property, rectangular Pt electrodes with widths of 150–200 µm were deposited on BFO surfaces with interelectrodes distances of 200–250 µm. I–V characteristics were measured under an illumination of a collimated violet laser (λ = 405 nm) with a power density of 380 W/cm2. In the striped-domain-structure BFO film with Pt electrodes fabricated along domain walls, above-band-gap open-circuit voltage (VOC) of 29 V was observed. In addition, single-domain-structured BFO thin film with Pt electrodes fabricated along also showed above-band-gap Voc of 26 V despite the absence of domain walls. It is considered that these large Voc values originated from the photovoltaic effect not at the domain walls but in bulk BFO.