Research On Photoelectric Detector Based On PZT Ferroelectric Thin Film

Ferroelectric materials have been widely used in the fields of sensors,actuators and ferroelectric memory due to their reversible spontaneous polarization.It is one of the research hotspots of new functional materials across the world.Recent studies have shown that ferroelectric materials have great application prospects in solar photovoltaic conversion due to their photovoltaic effect,mainly due to the anomalous open-circuit voltage and the generation mechanism of photogenerated carriers,which are not restricted by the bandgap width.Compared with the bulk materials such as ceramics,the thin films have faster response speed,higher photoelectric conversion efficiency,and are easier to be used in integrated circuits and systems,and it is found that ferroelectric thin films are especially suitable for application in integrated circuits and systems.A large photogeneration voltage can be generated under constant wavelength illumination,which makes it have potential application prospects in UV-IR detection field.Therefore,the photoelectric detection capability of PZT thin films is studied in this paper.Sandwich photodetectors based on Si?111?substrate were fabricated.ZnO/PZT and ITO/PZT thin films were prepared by RF magnetron sputtering.The thickness of PZT films was about 250 nm.Then metal Ag top electrode was deposited by resistive evaporation.The PZT thin films with these two kinds of bottom electrodes were characterized by XRD.Among them,the PZT films deposited on the ZnO substrate had obvious perovskite crystal structure,and their ferroelectric properties and anti-fatigue properties were better than those of ITO/PZT structures.The residual polarization intensity reaches 2.67?C/cm2,and passes through 108 poles.The residual polarization intensity is 95.4%of the original.The influence of the preparation process on the ferroelectric and photoelectric properties of PZT thin films was also studied in this paper.The sputtering atmosphere with different Ar/O₂ ratio was used.It was found that a small amount of oxygen?O₂12.5%?was added in the preparation.ZnO/PZT heterojunction can obtain better lattice matching,the uniformity of grain size is improved,the residual polarization intensity is7.14?C/cm²,and the light response degree of PZT thin film prepared in pure argon atmosphere is 0.2V/W in photovoltaic performance test.The experimental results show that the photoresponsivity is positively correlated with the ferroelectric properties and fatigue properties of the thin films.Finally,we fabricated PZT thin film photodetector on flexible substrate at low temperature?<260??,and fabricated PZT ferroelectric thin film on polyimide substrate.Compared with PZT thin film sample on Si substrate,there are many defects on the surface of the thin film.It leads to the decrease of ferroelectric properties.The saturation polarization intensity is 3.17?C/cm²,coercive field is 0.825 V,the residual polarization intensity is 11.09?C/cm²,flexible substrate,the photoresponse degree of the PZT thin film photodetector is 0.12 V/W at 340nm.The results show that the prepared The flexible PZT thin film detector is feasible in material structure and performance.