Hall-Bulk photovoltaic effect in BiFeO3/SrTiO3 at low temperatures

The bulk photovoltaic effect is considered promising for the next generation of solar cells as it could exceed the Shockley-Queisser limit. Studies have shown many materials have the bulk photovoltaic effect, however, the inner properties such as carrier mobility, relaxation time, etc., have been barely reported, largely hindering further understanding and utilization of the bulk photovoltaic effect. In this paper, we employ a Hall effect to study the transport properties of the bulk photovoltaic effect in a BiFeO3/SrTiO3 heterostructure. We interpret the magnetic field-dependent bulk photovoltaic currents using the fundamental Lorentz force law acting on photocarriers. A carrier transport with ~3 ps relaxation time, a mobility of 3.3×103cm2V−1s−1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$3.3\times {10}^{3}\,{{{{{{\rm{cm}}}}}}}^{2}{{{{{{\rm{V}}}}}}}^{-1}{{{{{{\rm{s}}}}}}}^{-1}$$\end{document} for the non-thermalised carrier and a mean free path larger than 50 nm are revealed. This is in good agreement with the ballistic transport mechanism. This work provides a generic approach to acquiring the basic characteristics of the bulk photovoltaic effect.