Disentangling electronic and thermal contributions to light-induced resistance switching in BaTiO3 ferroelectric tunnel junction

In the presence of asymmetric potential barriers, such as those created by imprint fields, ferroelectric polarization can be reversed by light due to the photoinduced suppression of polarization. Both thermal effects and photocarrier-induced polarization screening may agree with this experimental observation, challenging its understanding. Here, we explore light-induced ferroelectric polarization switching in BaTiO3 thin films. Time-dependent photocurrent and photoresistance experiments at different wavelengths indicate that the optical switch of polarization is mainly driven by photocarriers rather than thermal effects. The effect of light on sample polarization is found to be relatively slow and that an illumination period as long as ≈100 s is required to achieve complete switching when using a 405 nm light wavelength and 1.4 W/cm2 power density. It is shown that this response is governed by the concentration of photo-generated charges, which is low due to the reduced light absorption of BaTiO3 films at the explored wavelengths. Our conclusions can help us to better design optically switching devices based on ferroelectric materials.