Performance And Optimization Of Multiple-state Resistive Switching Memory Devices Based On Organic-inorganic Perovskite Thin Films

The traditional flash memory technology is facing a series of bottlenecks.The mainstream silicon-based memory has been difficult to meet the development needs of the electronic information industry in the high-speed development channel due to its low storage density,complex manufacturing process,and inability to apply to flexible devices.Resistive random access memory(RRAM)devices have been widely studied worldwide due to their simple structure,fast switching speed and low power consumption.Under the action of the bias voltage,the RRAM device can switch between two states of low resistance state and high resistance state,so as to realize the information storage of"0"and"1".With the emergence of new materials,titanium oxide materials,such as Ba Ti O₃,Sr Ti O₃,Pr_0.7Ca_0.3Mn O₃,have been extensively studied as active materials for resistive random access memory.However,inorganic perovskite materials usually require high temperature processing to prepare the active layer,which makes the device form a rigid structure and is fragile.Therefore,how to prepare flexible materials in the air environment to replace inorganic perovskites is currently a hot research direction.In recent years,organic-inorganic perovskite materials represented by CH₃NH₃PbI₃have received more and more attention in the development of RRAM due to the obvious hysteresis during the current-voltage(I-V)test.This paper focuses on the preparation and structural characterization of organic-inorganic hybrid FA_xMA_1-xPbI₃ perovskite films and their application and performance optimization in multilevel memory devices.Specifically include:1.Preparation and characterization of FA_xMA_1-xPbI₃ perovskite thin films:The perovskite thin films were prepared by a two-step solution method,with good compactness and high reproducibility during the experimental process.FA_xMA_1-xPbI₃ perovskite films with different compositions were prepared by changing the ratio of the precursor solution,and the morphology and structure of the films were characterized by means of SEM,XRD and visible absorption spectroscopy.2.Polymorphic memory performance of the device:The devices Ag/FA_xMA_1-xPbI₃/FTO prepared from different ratios of perovskite films all showed resistance switching phenomenon,and the Ag/FA_0.4MA_0.6PbI₃/FTO device showed good resistance switching phenomenon.When applying voltages in the order of 0 V?0.8 V?0 V?-1.4 V?0 V to the Ag electrode,three resistance states can be clearly seen from the IV curve of the Ag/FA_0.4MA_0.6PbI₃/FTO device.Variety.Without any protection,the device can be stably stored in air for about 7 days,and the time between different resistance states can be stably maintained for more than 1000 s.By analyzing its conductive properties,it is found that the memory device with the structure of Ag/FA_xMA_1-xPbI₃/FTO has an obvious space charge-limited conduction mechanism.3.Device performance optimization:The Ag/FA_0.4MA_0.6PbI₃/FTO device placed in the air environment for 7 days was tested,and it was found that the resistance switching phenomenon of the device almost completely disappeared,which may be due to the degradation of the perovskite film due to the contact of the perovskite film with the moisture in the air.,causing permanent damage to the device.A PMMA film was deposited on the FA_0.4MA_0.6PbI₃ perovskite film to isolate the perovskite layer from the air environment,and the performance changes of the device were studied under this condition.Devices with PMMA have better stability in air environment than ordinary devices;Using Pb Br₂ instead of PbI₂,and replacing the iodide ions in the FA_0.4MA_0.6PbI₃ film with bromide ions,the influence of the introduction of bromide ions on the resistance switching of the device was studied.It was found that with the increase of the proportion of bromide ions,the resistance switching phenomenon of the device disappeared gradually.