The Effect Of Electrodes On Performance Of TMDs RRAM

In recent years,with the explosive growth of big data scenarios,the traditional CMOS devices of the post-Moore’s era have reached the size limit and can no longer meet the storage and analysis needs of massive data.The RRAM provides a new solution for data storage and processing.Due to its small bandgap and excellent semiconductor performance,SnS₂ has shown great development potential in the field of resistive memory.However,CVD,hydrothermal and other"bottom-up"methods for the preparation of SnS₂ are costly and cannot meet the needs of industrial production,this thesis prepared uniform small-sized SnS₂ by liquid phase exfoliation method.RRAM has received widespread attention due to its high storage density and low power consumption.The choice of electrode has an important influence on the performance of resistive switching memory,but there is currently no consensus on the choice of electrode.The resistive type of common resistive memory is the metal conductive filament model,of which Cu and Ag conductive filaments are used most frequently.Therefore,this thesis studied the influence of different electrodes on the performance of Ag and Cu filament resistive switching memories.This thesis mainly achieved the following research results:（1）Large-sized SnS₂ was used as raw material to prepare small-sized SnS₂ using liquid-phase exfoliation methods（intercalation method,liquid-phase ultrasonic method,cell disruption method and ball milling method）.The product was analyzed using XRD for phase analysis,SEM and TEM for morphology characterization.The sizes of SnS₂ prepared by intercalation and liquid-phase ultrasound methods are in the micrometer range,which cannot meet the requirements of resistive switching memory for small sizes.SnS₂ prepared by cell disruption has a size ranging from 50 nm to 100 nm.The size of SnS₂ prepared by the ball milling method is about 50 nm,with uniform morphology and the highest yield,which can meet the needs of industrial production.The optimal process was determined to be ball milling the raw SnS₂ in HCON（CH₃）₂ solution for 72 hours,resulting in the production of uniform sheet-like SnS₂ with a size of 50 nm.（2）Four different electrode structures of（Ag,Cu,Al,Ti）/PMMA/SnS₂/Ag resistive memory were prepared,and the Ag bottom electrode was used as the positive electrode to study the influence of different top electrodes on the performance of SnS₂ resistive memory.The four RRAMs are all bipolar non-volatile RRAMs,and their resistive effects can be explained by the formation and breakage of Ag conductive filaments.HRS conforms to the ohmic conduction mechanism,and LRS conforms to the SCLC conduction mechanism.The Ag/PMMA/SnS₂/Ag RRAM can stably produce the resistive switching effect,so it is speculated that the Ag⁺needed to form conductive filaments is all produced in the Forming stage.The HRS of Ag/PMMA/SnS₂/Ag,Cu/PMMA/SnS₂/Ag,Ti/PMMA/SnS₂/Ag RRAM decreases in turn,so it is speculated that for Ag conductive filament RRAM,the lower the conductivity of the negative level,the lower the HRS of the device.Al/PMMA/SnS₂/Ag produces Al₂O₃ because of the electro-oxidation on one side of the Al electrode,resulting in its high resistance and low resistance being slightly higher than those of other electrodes.Ag/PMMA/SnS₂/Ag RRAM has high switching ratio and low operating voltage at the same time,and has the best resistive switching performance.Its switching ratio is greater than 10⁶,and the Set voltage is about 0.19V.（3）Four different electrode structures of（Cu,Ti,Al,Au）/PMMA/SnS₂/Ag resistive memory were prepared,and the Cu bottom electrode was used as the positive electrode to study the influence of different top electrodes on the performance of SnS₂ resistive memory.The（Cu,Al,Ti）/PMMA/SnS₂/Cu are all non-volatile RRAM.The high resistance of（Cu,Ti）/PMMA/SnS₂/Cu resistive variable memory is low,because the work function of Cu is relatively high,and multiple Cu conductive filaments are formed inside the device.The Al/PMMA/SnS₂/Cu is oxidized on the side of the Al electrode,resulting in relatively high resistance and low resistance of the Al/PMMA/SnS₂/Cu.The Au/PMMA/SnS₂/Cu RRAM is a interfacial RRAM.The effect of different current limits on the performance of Cu/PMMA/SnS₂/Ag RRAM is investigated.High current limits lead to lower high and low resistance of the device and higher Reset voltage.However,when the current limit is greater than a certain value,due to the Joule heat of the RRAM,the high resistance of the device will increase and the stability will deteriorate.