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)O-3 (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