Preparation And Resistance Switching Properties Of Lead Zirconate Thin Films

Currently,traditional memory devices are facing the challenge of miniaturization of electronic devices in the future.The feature size has reached the physical limit and cannot meet the development needs of high-density integration,high-speed processing,and low power consumption of future storage devices.Therefore,the research and design of a new type of non-volatile memory has become a focus of attention of researchers in recent years.Resistant memory devices using ferroelectric/antiferroelectric thin films as functional dielectric layers are expected to replace flash memory as one of the most powerful candidates for the next generation of non-volatile memory due to their simple sandwich structure,super fast storage speed,large resistance switching ratio,low power consumption and high reliability.At the same time,due to the good radiation resistance and rich physical properties of ferroelectric/antiferroelectric materials,they have great application potential in special fields such as complex space environments and multifunctional storage devices.In view of this,this paper uses the sol-gel method to prepare lead zirconate(Pb Zr O₃,PZO)antiferroelectric thin films,and investigates the influence of different annealing atmospheres and different substrate electrodes on the resistive effect of PZO thin film devices.At the same time,the performance of the antiferroelectric diode of the PZO film was explored,and the reverse diode effect under the prepolarization voltage was studied.(1)PZO films were prepared by sol-gel method on(LaNiO₃)LNO/Si substrate by annealing in different atmospheres(air,oxygen and nitrogen).The effect of oxygen defect concentration in PZO films controlled by annealing atmosphere on the resistance switching properties of PZO films was studied.Firstly,PZO thin films with moderate oxygen defect concentration were prepared by annealing in air atmosphere,and Au/PZO/LNO/Si devices were developed.The ?-? curve of the device at room temperature shows good bipolar resistance switching behavior,with a high-to-low resistance ratio of 10²,and stable cycle durability(>10²).Secondly,PZO films with different oxygen defect concentrations were prepared by annealing under oxygen and nitrogen atmosphere.XPS results show that the oxygen defect concentrations are 20.1%and 34.3%,and the corresponding device resistance ratios are 10 and 10⁵,respectively.But the cycle retention performance is not good.The results show that the oxygen defect concentration has a great influence on the resistive performance of the film.A high switching ratio corresponds to a higher concentration of oxygen vacancy defects,and a lower concentration of oxygen vacancies will cause the switching ratio to decrease,and even the hysteresis curve will disappear.The appropriate amount of oxygen vacancies in the film can enhance the resistance switching performance of the device.(2)The PZO functional films were prepared on the Pt/Ti/SiO₂/Si(Pt)substrate by the sol-gel method as the semiconductor layer,and the resistive performance of the Au/PZO/Pt device was studied.And the LNO film is introduced on the Pt substrate as the bottom electrode layer to fabricate Au/PZO/LNO/Pt memory cells.The comparative analysis results show that the optimized non-volatile Au/PZO/LNO/Pt memory cell exhibits better bipolar resistance switching characteristics,with lower operating voltage,higher on/off ratio(10²)and stable Cycle durability(10²).In addition,due to the difference in the bottom contact interface of PZO/Pt and PZO/LNO,the two types of memory devices exhibit two abnormal and normal bipolar resistance switching behaviors.The change of the interface Schottky barrier caused by the oxygen vacancy capture/release carrier and its oxygen vacancy migration can be used to explain the observed resistive switching effect.Studies have shown that the introduction of the LNO buffer layer on the Pt substrate as the bottom electrode can effectively improve the resistive performance of the PZO film,making it suitable for high-quality storage devices.(3)PZO thin films were prepared on FTO/Grass substrates by sol-gel method.The P-V hysteresis loop shows that when the applied voltage is greater than 8 V,the PZO thin films begin to exhibit good antiferroelectric properties.The ?-? curve does not show obvious hysteresis when the prepolarization voltage is not applied at the beginning.After prepolarization at 15 V,the ?-? curve shows obvious hysteresis characteristics of the rectifier diode,and the hysteresis window also increases with the increase of the scanning voltage.At0.5 V,1 V,1.5 V and 2 V voltages,the ratio of storage window switch is 5,10,20 and 100,respectively,indicating the potential application value of Au/PZO/FTO devices in the field of multi-valued storage.In addition,by applying different prepolarization voltages to the Au/PZO/LNO/Si devices developed by air annealing samples,the ?-? curves of the devices in the±2 V voltage region were measured,and the reverse diode phenomenon was obtained.Comprehensive analysis shows that the generation of resistive switching behavior at low voltage has a greater correlation with the oxygen defect concentration,and the generation of its inverted diode is related to the prepolarization voltage greater than its coercive voltage.