Impacts of light on switching properties of epitaxial (Pb0.9La0.1)(Zi0.4Ti0.6)O3 capacitor with Al2O3 doped ZnO top electrode

Abstract

Epitaxial (001) (Pb0.9La0.1)(Zi0.4Ti0.6)O3(PLZT)/La0.5Sr0.5CoO3(LSCO)/SrTiO3(STO) heterostructure was prepared by radio frequency (RF) magnetron sputtering, and Al2O3 doped ZnO (AZO) film was used as the top electrode to fabricate AZO/PLZT/LSCO capacitors in order to investigate the influence of light on electrical and optical properties of the capacitors. It was found that remanent polarizations of the capacitor are 25.7 μC/cm2, 23.3 μC/cm2, 20.7 μC/cm2, 31.3 μC/cm2 under the light intensity of 80 mW/cm2, 100 mW/cm2, 120 mW/cm2, and the dark condition, respectively. Remanent polarization (Pr) is obviously reduced upon illumination, which is attributed to the pinning of captured photogenic carriers on ferroelectric domains. The leakage current densities are 2.1 ×10−4 A/cm2, 2.69 ×10−4 A/cm2, 3.60 ×10−4 A/cm2 and 4.82 ×10−4 A/cm2 at 250 kV/cm and 2.1 ×10−4 A/cm2, 2.57 ×10−4 A/cm2, 3.58×10−4 A/cm2 and 4.62 ×10−4 A/cm2 at −250 kV/cm, respectively. The leakage current density upon illumination is bigger than that under dark condition, and satisfies of the capacitors satisfy the limited space charge conduction under the condition of higher electric field, and Ohmic conduction mechanism under the condition of lower electric field. It is found that illumination does not change the leakage mechanism, but impacts the leakage current density.