Effects of light on ferroelectric polarization and leakage current

We report the enhancement of polarization in polycrystalline ferroelectric thin films under illumination of light. The (Pb0.6Li0.2Bi0.2) (Zr0.2Ti0.8)O3 (PLBZT) thin films were fabricated on a Pt/TiO2/SiO2/Si (100) substrate by pulsed-laser deposition (PLD) technique. The illumination of weak monochromatic light having a wavelength comparable to the bandgap of PLBZT showed the development of non-equilibrium charge carriers which enhance switchable polarization and displacement current. A Positive-up Negative-down (PUND) analysis also supports the enhancement of switchable polarization under illumination. The fatigue test indicates nearly 20-30% decrease in polarization after a long time write and read cycles. These results may provide an extra degree of freedom to create electrical WRITE and optical READ logic states.