Preparation And Synaptic Emulation Of Memristors Based On MoS₂ Film

Compared with the traditional von Neumann architecture system,memristor is similar to biological synapses and neurons,and has the advantages of smaller size,fast response speed and short time,low power consumption and large-scale integration.Constrained by hardware（material,mechanism,stability,power consumption and process integration,etc.）and software（training,algorithm and self-learning,etc.）,there are still challenges.The road to building a brain-like computer with memristors is still long.Many researchers are committed to developing new memristor,improving the structure of memristor,and selecting new functional layer materials,so as to realize the application of memristor in different fields such as visual recognition,speech parsing,task decision-making,operation control and so on.Among various resistive materials,MoS₂ as a two-dimensional（2D）nanomaterial has obvious advantages in adjustable bandgap,carrier concentration,high integration density and flexible wearable.Especially,MoS₂ is popular in the field of memristor because it has tunable resistance and can simulate synapses.However,the current MoS₂ memristor architecture is still dominated by the traditional sandwich stack.Due to the random and damaging formation and fusing of memristor channels in the atomic layer,the stability of the device is insufficient.In view of this problem,this thesis carries out research under the title of"Preparation and synaptic emulation of memristors based on MoS₂ film".The main contents include the following two aspects:（1）Large area,uniform density and good crystalline MoS₂ thin films were prepared by two-step method,namely PLD-assisted CVD method,and the memristor devices with Cu/MoS₂/Cu planar structure were designed and fabricated.The results show that the device operates at low voltage,has the characteristics of bipolar electronic resistance switch,has good stability and repeatability,and the current has no obvious attenuation after more than 600 cycle scanning.retention time up to 10⁴ s,with non-volatile characteristics.Finally,mechanism fitting showed that the prepared devices were consistent with defect-dominated SCLC mechanism.This study provides a feasible method for the preparation of planar memristor based on MoS₂ thin film.（2）The planar Cu/MoS₂/Cu memristor was used to simulate synapses.The results show that the device can well simulate some basic learning behaviors of neural synapses,such as paired pulse facilitation（PPF）,short-term plasticity（STP）and long-term plasticity（LTP）.It is found that the transition from STP to LTP can be achieved by using multi-spike sequences,that is,the transition from short-term memory to long-term memory.These results indicate that MoS₂ thin film memristor has a wide range of potential applications in biological synapses.