We examine the photo-assisted polarization loop in a BiFeO₃ thin film under UV light illumination. BiFeO₃ thin film prepared by pulsed laser deposition method onto the BaTiO₃ thin film and the polarization behavior has been measured under poling voltage. Our results show the engineered polarization due to controllable schottky barrier under inverse poling voltage. This control on schottky barrier height and then polarization of thin film can be opened the new insight in the ferroelectric devices.