Fabrication Of ZnO Based Memristive Devices And The Study Of Synaptic Emulation

With the rapid development of artificial intelligence,the construction of artificial neural network has become an urgent need.Memristor,as a new electronic device,has a potential application prospect in the field of synaptic emulation because of its nonlinear transmission characteristics similar to that of the synapse.Oxide is an important material system for constructing memristors,and ZnO has become a base material for constructing memristors because of its advantages such as high chemical stability,abundant material reserves and environment friendly.However,on the one hand,there are a large number of intrinsic defects(such as O vacancy)in ZnO,which leads to a high concentration of the film carriers and high energy consumption in the operation of ZnO based memristor.It cannot meet the needs of brain-like synaptic devices.Therefore,it is urgent to develop ZnO based memristor devices with low power consumption.On the other hand,the development of photoelectric learning synaptic devices is an important branch of the construction of efficient brain-like neural networks in the future,and the good photoelectric properties of ZnO materials provide a good platform for the development of photoelectric synaptic devices.This paper was based on the above requirements to conduct the research,and the specific research contents are as follows:1.Study on ZnO based ultralow power consumption memristive device:The structure of Au/ZnO:N/TiN/PET memristive device was constructed by magnetron sputtering with ZnO:N films.The self-compensation effect of N-doped ZnO thin films was used to reduce the concentration of film carriers and the device operating current,which achieved ultralow power consumption in the device.By continuously adjusting the N pressure in the preparation process and optimizing the N/Zn ratio in the film,a stable ZnO based ultralow power memristor was obtained.The power consumption in single operation was only 60 f J,which was comparable to biological synapses(<100 f J).Furthermore,the temperature dependent ion diffusion process indicated that the physical mechanism of the device came from oxygen ion migration and diffusion.Meanwhile,in the electrical characteristic test,the synaptic learning functions such as Excitatory Post Synaptic Current,Pared Pulse Facility,Spike Timing Dependent Plasticity and Experience Dependent Plasticity were simulated by changing the parameters including amplitude,width,quantity and frequency of electrical pulse.2.Study on ZnO based photoelectric memristive device:The structure of Au/HfO_x/ZnO/ITO memristive device with HfO_x/ZnO heterojunction was fabricated by magnetron sputtering.The results of electrical properties and absorption tests showed that the device could produce persistent photoconductance after being stimulated by a light pulse at a wavelength of 390 nm.At the same time,this continuous photoconductance phenomenon was used to simulate the photoelectric synaptic learning functions,such as short-term/long-term plasticity and experiential learning behavior,which was obtained by adjusting the parameters of optical pulse intensity,time and frequency.In addition,the synergistic stimulation of light pulse and electric pulse is used to realize the photo potentiation and electrical inhibition in biological learning.