Memristor Based On ZnS Thin Film And Its Application In Photoelectric Synapse Device

In recent years,more and more applications of artificial intelligence have changed human life style to a great extent.At the same time,it also puts forward new requirements for the development of artificial intelligence technology.At present,the artificial intelligence tools used are based on the deep artificial neural network realized by the traditional von Neumann computer.Its data processing unit and storage unit are physically separated,the data transmission unit is independent,and its operation is seriously limited.Neuromorphological computing aims to build a computer that can simulate the biological process of human brain.It is a promising solution to realize artificial intelligence.Memristor has simple three-layer structure,high integration and excellent digital and analog functions,so it is expected to become the constituent unit of the next generation neuromorphological computing system.ZnS is a II-VI direct wide band gap compound semiconductor with a band gap of 3.5-3.7 e V.It has rich raw materials,low toxicity and excellent photoelectric properties.It is widely used in the fields of photodiodes,thin film solar cells,photoelectric detection and electroluminescence.At the same time,ZnS based composites are also widely used to prepare memristors with good properties.Therefore,ZnS thin film is used as the dielectric layer in this paper.ZnS thin film was prepared by thermal evaporation equipment as the dielectric layer of the memristor.The memristor based on ZnS thin film was obtained by adjusting the process parameters of the thin film.Firstly,memristors with different top electrodes were prepared.After comparison,it was found that Au/ZnS/Pt had excellent electrical properties.After comparing the deposition temperature of ZnS film,it is found that ZnS film grown at 500?has good compactness and better film performance.The electrical test of Au/ZnS/Pt memristor shows that the device has good electrical performance,good cycle characteristics and holding characteristics,and has an ultra-high switching ratio of more than 10¹⁰,which is the highest compared with the same type of devices,indicating that the device has excellent digital storage performance.Based on Au/ZnS/Pt memristor,the optical signal is introduced into the working mode of the device,and two freely switchable modes of photocurrent enhancement and photocurrent attenuation are obtained.The mechanism is caused by the capture/decapture behavior of light excited electrons in the film.On this basis,the effects and laws of different light conditions,including optical power density,wavelength and illumination time,on the performance of the device are explored.At the same time,the device has ultra-low power consumption,and the power is in the order of p W.Finally,the biological short-range plasticity controlled by light and the functions of paired pulse facilitation(PPF)and paired pulse depression(PPD)of synapse are simulated,and the results consistent with the biological synapse are obtained by fitting function.The simulation of visual light and shade adaptation is further realized.In this study,a memristor based on ZnS film and a dual-mode device with photoelectric synapse function are prepared,which has an ultra-high switching ratio of more than 10¹⁰.At the same time,the application of optically controlled biological synapse simulation and visual adaptation is realized.The device has great application potential in the field of digital storage and machine vision.