Switchable ferroelectric diode and photovoltaic effects in polycrystalline BiFeO3 thin films grown on transparent substrates

Abstract

Switchable ferroelectric diode and photovoltaic effects in epitaxial BiFeO3 (BFO) thin films have drawn intense attention for its potential applications in resistive memory and solar cell. However, both of these two effects were observed almost entirely in epitaxial BFO thin films or bulk crystal. In this paper, we demonstrate these effects in a polycrystalline BFO thin film grown on a transparent Indium Tin Oxide (ITO) covered quartz plate by the pulsed laser deposition technique. The BFO thin film shows good ferroelectricity with remanent polarization of around 60 μC/cm2 and has a direct band gap of 2.64 eV. The current-voltage curves measured at an Au/BFO/ITO configuration show diode-like rectifying characteristics, and the diode polarity can be reversed with polarization switching. The polycrystalline BFO thin film also exhibits a switchable photovoltaic effect with an open-circuit voltage of approximately 0.2 V and a short-circuit current of nearly 60 μA/cm2 under illumination. This study demonstrates that the polycrystalline BFO thin film on a transparent substrate also has the ferroelectric switchable diode and photovoltaic effects. Therefore, these results will be useful to expand the application of BFO thin films in optoelectronic devices.