Conduction mechanism and switchable photovoltaic effect in (111) oriented BiFe$_{0.95}$Mn$_{0.05}$O$_{3}$ thin film

TL;DR

This study investigates the conduction mechanisms and switchable photovoltaic effect in (111) oriented BiFe$_{0.95}$Mn$_{0.05}$O$_{3}$ thin films, revealing temperature-dependent conduction models and a large, switchable photovoltaic response.

Contribution

It demonstrates the coexistence of bulk and interface conduction mechanisms and the ability to switch the photovoltaic effect with voltage pulses in the material.

Findings

Both Poole-Frenkel and Schottky conduction mechanisms are present.

The photovoltaic effect can be switched by voltage pulses.

Large open circuit voltage observed at low temperatures.

Abstract

Epitaxial 200nm BiFe$_{0.95}$Mn$_{0.05}$O$_{3}$ (BFO) film was grown by pulsed laser deposition on (111) oriented SrTiO3 substrate buffered with a 50nm thick SrRuO$_{3}$ electrode. The BFO thin film shows a rhombohedral structure and a large remnant polarization of Pr = 104 $\mu$C/cm$^{2}$. By comparing I(V) characteristics with different conduction models we reveal the presence of both bulk limited Poole-Frenkel and Schottky interface mechanisms and each one dominates in a specific range of temperature. At room temperature and under 10mW laser illumination, the as grown BFO film presents short-circuit current density (Jsc) and open circuit voltage (Voc) of 2.25mA/cm$^{2}$ and -0.55V respectively. This PV effect can be switched by applying positive voltage pulses higher than the coercive field. For low temperatures a large Voc value of about -4.5V (-225kV/cm) is observed which suggests a bulk non-centrosymmetric origin of the PV response.