Performance Optimization And Mechanism Exploration Of Zinc Oxide Based Memristor

In the era of big data,the processing and storage of information is particularly important.At present,the mainstream non-volatile storage technology is mainly based on flash memory,but it is facing technical bottlenecks such as high write voltage,slow erase and write speed,large power consumption and difficulty in further miniaturization.The next-generation nonvolatile memory such as ferroelectric memories,phase change memories,magnetoresistive memories,and memristors have received widespread attention.Among them,memristor devices have the advantages of simple structure,fast operation speed,small feature size,high storage density and low power consumption,and are expected to replace flash memory as the next generation of mainstream non-volatile memory devices.The thesis first studies the memristor with zirconium-doped zinc oxide as the resistive switching layer.FTO/Zr:Zn O/Pt device was prepared by sol-gel method.The result shows that when the zirconium doping content is 10%,the device shows typical bipolar resistive switching properties and a satisfied uniformity of the operating voltage and the resistance distribution.By altering different compliance current during the set process,the device obtains multi-level storage capability,which provides an experimental basis for the memristor in high-density storage applications.The thesis focuses on the Ti N/Hf:Zn O/Pt memristor with Hf element doped Zn O film as resistive switching layer.Compared with the Ti N/Zn O/Pt device,the resistive switching layer is effectively doped with 5.70%Hf,and the device has stable resistive switching properties and up to 10~8pulse endurance.According to the current fitting results of the devices,we find that the Ti N/Zn O/Pt device is space charge limiting current mechanism in the high resistance state,while the Ti N/Hf:Zn O/Pt device is the Schottky emission mechanism in the high resistance state.Combined with x-ray photoelectron spectroscopy,it is known that the doping of Hf element introduces more non-lattice oxygen into the Zn O resistive switching layer,which can modify the performance of oxygen vacancy conductive filament memristor.The doped Hf element can concentrate oxygen ions and help to reduce the randomness of the CF formation and rupture.Thus the resistive switching stability of the device was improved.Finally,the thesis studies the Ti N/IGZO:N/IGZO/Pt device with a nitrogen-doped ultra-thin indium gallium zinc oxide(IGZO)layer.Compared with Ti N/IGZO/Pt devices,the forming voltage of Ti N/IGZO:N/IGZO/Pt device is decreased.Resistive switching parameters such as resistance high and low resistance distribution,Set voltage distribution,and pulse endurance are all significantly improved.We conclude that the IGZO:N inserting layer can act as an oxygen reservoir buffer and concentrate oxygen ions around the conductive filament tip,making it easier for the redox reaction to happen.Thus the uniformity of resistive switching parameters of the device was enhanced,as well as the pulse endurance.In summary,the thesis aims to optimize the resistive switching properties of the Zn O-based memristor device by using doping method and designing bilayer structure,and to study the resistive switching mechanism of the device.Our work provides experimental basis and theoretical basis for the application of Zn O-based memristor,which has important scientific and theoretical significance.