Study On Optically Controlled Storage Characteristics Of Resistive Memory Based Halide Perovskite

In the information age,new industries such as cloud computing and the Internet of things are emerging,and the amount of daily data is growing exponentially.People's demand for the integration,miniaturization and multifunction of memory,one of the information carriers,is becoming more and more urgent.However,due to the approaching of the limit size of silicon-based memory,the traditional memory is close to the limit in terms of high density and integration.In order to better meet the storage requirements,various new storage modes and devices came into being.Among them,resistive random access memory(RRAM)is regarded as the most potential new nonvolatile resistive memory because of its simpler structure,faster reading and writing,higher integration and other advantages.For RRAM,the physical characteristics of the resistive functional layer mainly affect the resistive performance of the device.The previous method of data storage by single electric field regulation shows disadvantages in device miniaturization and storage integration.Therefore,in recent years,based on the physical characteristics of materials,people expect to realize the coordinated regulation of resistance variation characteristics by introducing multiple external fields,so as to realize the requirements of high density,low power consumption and device integration of resistance variation storage.Among many materials with resistance effect,perovskite halides have become one of the research hotspots of materials because of their excellent photoelectric properties.They have long been widely used in the field of optoelectronic devices such as solar cells and photodetectors.In recent years,they have shown great development prospects in the field of resistance random storage,but the research on photoelectric cooperative regulation of resistance characteristics is relatively scarce.For the rapid development of halide perovskites in the field of optical controlled storage,it is still necessary to provide a large number of experimental and theoretical data as guidance.This paper is mainly about the study of the resistive properties of halide perovskite materials.With CsPb₂Br₅-CsPb Br₃,Cs₂AgBiBr₆ and Cs₂AgBiBr_6-xCl_x as the research carrier,a series of thin film samples were obtained by sol-gel method,and the resistance mechanism under the synergistic control of photoelectric field was explored.The research contents and results show as follows:1.Study on resistance variation characteristics in CsPb₂Br₅-CsPb Br₃.Firstly,flat and compact CsPb₂Br₅ and CsPb₂Br₅-CsPb Br₃ sample films were prepared on ITO substrate,and Au electrodes were plated by sputtering to form devices.Through the resistance variation characteristics test of CsPb₂Br₅,CsPb₂Br₅-CsPb Br₃ and other devices under light(520 nm)and no light conditions,it is known that Au/CsPb₂Br₅-CsPb Br₃/ITO device retains the original stable bipolar resistance variation characteristics of CsPb₂Br₅ film under the applied voltage,the ON/OFF state ratio is 500,the data holding time is 2000 s,and the device can be read for 400 times.Due to the photoelectric characteristics of CsPb₂Br₅-CsPb Br₃,the light field can effectively regulate the resistance characteristics.Under 520 nm illumination,the multi-resistance state performance of the device can be induced by changing different light radiation intensity,and the four-state storage can be realized.Through the analysis of the data system,the resistive storage behavior of the device is mainly controlled by the SCLC mechanism dominated by bromine vacancy.Under the action of an external electric field,the charge capture/release of bromine vacancy in CsPb₂Br₅-CsPb Br₃ is reversible,and the high and low resistance switching of the device is realized.At the same time,the reversible change of the Schottky-like barrier at the Au/CsPb₂Br₅-CsPb Br₃ interface in electric field also contributes to the resistance characteristics.When the film is radiated by light,it will produce photocurrent.With the change of light intensity,there will be polymorphic resistance behavior.2.Study on the optically controlled resistance variation characteristics and mechanism of Cs₂AgBiBr₆ based RRAM.Firstly,Pt/Cs₂AgBiBr₆/ITO devices exhibit bipolar resistive behavior under the electric field.After that,under the 445 nm and 4.67 m W/cm~2 light radiation,the resistance variation performance of the device has been effectively improved:Under 445 nm illumination,the device with a storage window of 100 showed no obvious deterioration after 2400 s and 300 scan voltage cycles,it shows three resistance states under the action of different set voltages.The analysis shows that the bromine vacancy acts as a defect in the film and participates in the resistance behavior,in which the Schottky barrier also plays a certain role.Optical radiation modulates Schottky barrier by affecting interface holes,indirectly adjusts the resistance behavior and optimizes the resistance performance of the device.3.Study on the resistive performance of Cs₂AgBiBr_6-xCl_x based RRAM.Similar to Cs₂AgBiBr₆ devices,Cs₂AgBiBr₅Cl films with the largest amount of chlorine were prepared by sol-gel method,and a Pt electrode was sputtered on the film to form Pt/Cs₂AgBiBr₅Cl/ITO devices.The resistive performance of the device was tested under no light and with light(445 nm,4.67 m W/cm~2)to explore the effect of the Cl element on the resistive performance of the device.The test results show that under the condition of no light,the ON/OFF state ratio of the device is 10 and the maintenance time is about 2500 s,Under the condition of light,the device with a storage window of 100 can maintain 2500 s.The stability of the device is slightly better than that of the CABB device,and the resistance variation performance is similar to that of the CABB device.Due to the low doping amount of Cl,the effect of Cl on the resistive performance of Pt/Cs₂AgBiBr₆/ITO devices is not obvious.Based on the experimental phenomenon,a small amount of Cl doping slightly improves the stability of the device.In the later stage,the experimental preparation scheme needs to be further improved to prepare Cs₂AgBiBr_6-xCl_x films with a larger doping amount and explore their resistance variation properties.