Large electroresistance and tunable photovoltaic properties of ferroelectric nanoscale capacitors based on ultrathin super-tetragonal BiFeO3 filmsElectronic supplementary information (ESI) available: Details of patterning of top nanoelectrodes by the polystyrene sphere template method, photovoltaic properties of BFO nanocapacitors with different sizes, and interface Schottky barrier profiles in the dark and under light illumination derived from the fitting of I-V curves. See DOI: 10.1039/c6tc046

Ferroelectric nanocapacitors with simultaneously tunable resistance and photovoltaic effect have great potential for realizing high-density non-volatile memories and multifunctional opto-electronic nanodevices. Here, using a polystyrene sphere template method, we developed well-ordered Au nanoelectrode arrays on super-tetragonal BiFeO 3 (T-BFO)/La 0.7 Sr 0.3 MnO 3 (LSMO) epitaxial thin films, forming Au/T-BFO/LSMO nanocapacitors. The nanocapacitors exhibited switchable resistance states and photovoltaic responses, controllable by the ferroelectric polarization of T-BFO. Owing to the giant polarization of T-BFO, both giant electroresistance (ON/OFF current ratio >20 000) and noticeable photovoltage (∼0.4 V) were achieved in the Au/T-BFO/LSMO nanocapacitors. These results demonstrate that the T-BFO-based nanocapacitors are promising for applications in high-density memories with multiple routes for non-destructive readout, as well as other multifunctional nanodevices. Ferroelectric nanocapacitors with tunable resistance and photovoltaic effect have potential for multifunctional opto-electronic nanodevices.