Research On Ag/MoS₂/Ti Resistive Random Access Memory And Its Optimization Scheme

In the past few decades,as one of many alternatives to typical silicon-based memory,resistive random access memory(RRAM)has excellent performance such as easy construction,fast operation,strong scalability,and multi-value storage.Stand out from the army and become a potential candidate for future NVM devices.Therefore,finding suitable functional materials for RRAM is an important research field.Compared with many traditional materials used before,two-dimensional(2-D)materials have incomparable optoelectronic properties,especially in high-performance,new-function optoelectronics.The application aspect of the device exhibits remarkable nonlinear optical characteristics.Two-dimensional materials such as GR,MoS₂,h BN,WS₂,Mo Te₂,and MoSe₂have been introduced as the active layer sandwiched between two conductive electrodes to form RRAM devices on flexible and rigid substrates.Among them,MoS₂ is an inorganic two-dimensional material that is particularly worthy of attention.Until now,the scientific research field has invested a lot of attention on MoS₂ two-dimensional materials and explored its performance in resistive random access memory.For example,RRAM with metal as the electrodes at both ends has good performance,but the mechanism research is not complete.Especially in the metal/MoS₂/Ti/Si devices,what kind of phase MoS₂ belongs to as a functional material has not been reported.Therefore,this paper uses first-principles methods from the micro level to study the performance of 2H phase MoS₂ in RRAM,and on this basis,to improve the device by inserting a graphene layer on the top electrode and the MoS₂ layer.The effect of performance.First,we studied the resistive characteristics of Ag/MoS₂/Ti devices.After determining the surface construction form of the electrode and the resistive layer,the layout analysis determined that the interface was constructed in the form of edge contact.We used molecular dynamics simulation to simulate the formation process of the conductive filament,which shows that the device is indeed conducted by the conductive filament.Finally,the I-V characteristics prove that Ag/MoS₂/Ti RRAM has resistive characteristics and is dominated by 2H-phase MoS₂.Then we optimized on the basis of the original device and added a Graphene layer between the top electrode and MoS₂.For this reason,we proposed a 2×2/?3×?3 GR/MoS₂interface to match the electrodes at both ends of the device.After building the model,we compared it with the two GR/MoS₂ interfaces used in the past.Then using graphene and MoS₂ and the comparison of the projected energy band of the interface,it is found that the newly proposed interface is closer to the interface of 4×4/3×3 ratio.Then through the work function of the three,the schematic diagram of the charge transfer and the charge density difference between the interface and the device,it can be observed that the charge transfer at the interface generates an internal electric field.This internal electric field is the main reason for the addition of the GR layer to improve the performance of the device.In addition,the electron transport characteristics of the GR layer in the device are analyzed,and the non-resistive switching characteristics of the GR layer devices are obtained.Therefore,GR plays an auxiliary role in the devices with MoS₂ as the resistive switching layer.Finally,the performance of Ag/GR/MoS₂/Ti RRAM is analyzed through its I-V characteristics.Compared with RRAM devices that only use MoS₂ as the intermediate material,the switching ratio and current drive capability of the device after inserting the GR layer are significantly better than that of the original device.In summary,compared with the Ag/MoS₂/Ti RRAM based on three layers of MoS₂,the RRAM based on GR/MoS₂ has excellent and stable resistance change characteristics.This work has a certain reference value for the experimental research of Ag/MoS₂/Ti devices,and provides a new way to improve the performance of related devices.