Ferroelectric Photovoltaic Effect

Abstract

Tetragonal BiFeO 3 films with the thickness of 30 nm were grown epitaxially on (001) ori - ented LaAlO 3 substrate by using pulsed laser deposition (PLD). The transverse photovol - taic effects were studied as a function of the sample directions in-plane as well as the angle between the linearly polarized light and the plane of the sample along X and Y directions. The absorption onset and the direct band gap are ~2.25 and ~2.52 eV, respectively. The pho - tocurrent depends not only on the sample directions in-plane but also on the angle between the linearly polarized light and the plane of the sample along X and Y directions. The results indicate that the bulk photovoltaic effect together with the depolarization field was ascribed to this phenomenon. Detailed analysis presents that the polarization direction is along [110] direction and this depolarization field induced photocurrent is equal to ~3.53 μA/cm 2 . The BPV induced photocurrent can be approximate described as Jx ≈ 2.23cos(2 θ ), such an angu lar dependence of photocurrent is produced as a consequence of asymmetric microscopic processes of carriers such as excitation and recombination.