Research On Memristor And Biomimetic Neural Devices Based On Two-dimensional In₂S₃

The name of‘memristor’is a combination of the memory and resistor,refers to a kind of resistor that has memory.As the basic circuit element,memristor is a circuit device that expresses the relationship between magnetic flux and electric charge.A memristive device has the dimension of resistance,but unlike resistance,the resistance of a memristive device is determined by the amount of charge going through it.Therefore,by measuring the resistance value of the memristor,one can acquire the amount of charge that has gone through it,which has the effect of memorying charge.The emergence of memristive devices in nano scale is expected to realize non-volatile random access memory.Memristive devices have a series of advantages such as simple structure,fast reading and writing speed,low power consumption,and high storage density.They are expected to break the bottleneck of the von Neumann structure and break through the limit of Moore’s Law.Analog-digital state logic computation and brain-like neural computation are two ways for memristive devices to realize the functions of information storage and computation.Despite the explosive growth of memristive device research,it is still in its infancy and there are still many unsolved problems in memristive dielectric materials,resistive switching mechanisms,analog plasticity,reliability,heterogeneous integration,and multifunctional realization.Therefore,developing new memristive materials,exploring the resistance-change mechanism in multiple ways,clarifying the law of parameter evolution,and expanding functions（such as simulating neural synapses,digital recognition,and logical operation functions,etc.）is urgently needed in this research field.Two-dimensional materials have broad application prospects in the fields of electronics,storage and optoelectronic devices due to their unique tunable electronic structures and rich physical and chemical properties.In this thesis,two-dimensional non-layered In₂S₃ material is used as the functional dielectric material of memristive devices.The material preparation,memristive mechanism,memristive performance,realization of bionic function,application in memristive devices are explored.In this thesis,physical vapor deposition（PVD）growth technology is used for material preparation.Powder of semiconductor material In₂S₃ is used as the source,and mica is used as the substrate.Based on the In₂S₃ thin film,a memristive device with two-dimensional In₂S₃as the resistive-variable dielectric layer was fabricated by standard photolithography.The properties of the memristive device and its application in bionic neuromorphic devices were studied accordingly.The results of the study are summarized as follows:1.The two-dimensional In₂S₃ thin film was successfully grown and prepared,and the Au/In₂S₃/Au memristive device based on the systheized In₂S₃ thin film was constructed by wet transfer and standard photolithography process.The I-V resistance hysteresis loop,resistance switch ratio,conductance modulation and other properties were measured and analyzed.The regulation of gate voltage and the influence of different metal electrodes on memristive properties were studied and analyzed.The working mechanism of memristive materials is studied using different metal electrodes with different potential barriers.Simulating synaptic plasticity,excitatory post-synaptic current（EPSC）has been successfully realized.The dependence of the number of spike stimulation on excitatory postsynaptic potential（EPSP）,the modulation of weight connection strength and the transition from short-term memory（STM）to long-term memory（LTM）were also studied.2.A memristive device on flexible thin mica substrate is constructed to act as an artificial nociceptor that can respond to stimulis of optoelectronic signal.Because of the memristive resistance of the 2D In₂S₃ film and related good synaptic plasticity,as well as the good photoresponse characteristics,the device can respond to signal of electrical and optical pulse simultaneously.By proper setting（frequency,amplitude,time）of the stimuli of the electrical or optical pulse signal as input,the artificial optoelectronic nociceptor based on the In₂S₃ film can effectively show complete nociceptive behaviors of‘threshold’,‘inadaptation’,‘relaxation’and‘sensitization’behaviors of the biological nervous system.The research work provides an effective demonstration of the artificial optoelectronic nociceptor with memristive devices by realizing response to multiple external stimuli and diverse functions,which is expected to be applied in the field of biological sensor.