Here we present our results of a large photoconductivity in ultra-thin epitaxial layers of LaTiO3 (LTO) grown on SrTiO3 (STO) single crystal surfaces on exposure to ultraviolet light. We note that the change in conductivity on photo-exposure can be modulated by an electric field applied in field effect transistor geometry. We present a scenario where electrons from the lower Hubbard band of LTO and oxygen defects states of STO accumulate at the interface. The extent of this accumulation is modified by electric and photon fields giving rise to a potentially new electronic device. © 2011 American Institute of Physics.