Study On Resistive Switching Mechanism And Properties Of TiO_x-based RRAM With Inserted Metal Layer

The research of Resistive Random Access Memory(RRAM)has been developing for decades.Although the finished products are available,the resistive switching mechanism is not so clear that it is still the focus of study at present.In principle,RRAM is divided into two categories.One is the ionic type RRAM with outstanding performance of endurance and retention while it accompanies with high power consumption and weak reliability.The other one is the electronic type RRAM with excellent uniform,low power consumption,easy integration of high density,and so on.However,the development of the electronic type RRAM is restricted by the poor performance of endurance and retention.In this paper,the ability of endurance and retention was improved by changing the thickness of TiO_x layer and inserting metal layer(Al,Ti,V)into the interface of the device based Al/TiO_x/Al structure.The Al electrodes in this structure were deposited by electron beam evaporation,while the deposition of TiO_x film was used by magnetron sputtering and the preparation of metal layer made use of ion beam sputtering.Meanwhile,the samples were analyzed by material characteristic test methods such as Atomic Force Microscope(AFM),X-ray Photoelectron Spectroscopy(XPS),and Aglient B1500 A.In this thesis,firstly,the impact of the thicknesses of TiO_x on endurance performance in ATA structure were investigated.By linear fitting of the logI-logV curves in switching cycles,it was found that the thicknesses of TiO_x thin film was a significant factor,which could have an effect on electron trapping and detrapping at defects centers,and also further verified the electronic resistance switching mechanism of ATA structure device.Secondly,the following experiment were designed by inserting metal layer(Al,Ti,V)into the top interface of the device based the appropriate thickness of TiO_x layer.This proved that the performance of device was improved by inserting Al,Ti layer,while the thickness of metal layer was one of the most important factors to control the performance of the sample.Finally,through the study of the temperature testing of all components,this proved that the inserting Al layer process could effectively keep trap density of the devices and inserting Ti layer could enhance trap density of the devices so that the performance could be improved after estimating the activation energy values of different samples under different cycles.In this study,it proved that the ability of endurance and retention of electronic type RRAM could be enhanced by changing the thickness of TiO_x layer and inserting metal layer into the top interface of the device based Al/TiO_x/Al structure.In addition,we analyzed the resistive switching(RS)mechanism based on the device with the inserted layer and established a new model,which provided useful information on the general features of the electronic bipolar resistive switching(eBRS),which could also be applicable to other binary(or even ternary)metal–oxide RS systems based on the electronic switching mechanism.