Resistive Switching Effect And Its Application In On-chip Nano Devices

Recently,resistive switching（RS）effect has attracted intensive attention.Devices based on RS effect possess outstanding properties,including simple structure,high integration density,low power consumption,fast response speed,high on/off ratio and CMOS compatible integration process.These properties indicate RS devices have potential applications in reconfigurable logic circuits,neuromorphic computing and most importantly,non-volatile memories.However,the RS mechanism is still on hot debate,which seriously hinders it development in practical application.Therefore,in this paper,by combining experimental measurements,theoretical analysis and simulations,we systematically investigated RS effect in Ag/Si O₂,LDH and TaS₂,results are shown below:（1）To investigate RS effect in Ag/Si O₂ structure in situ,we creatively combined graphene FET with Ag/Si O₂ to form a self-monitored device.In this device,graphene works as a local sensor to continuously record the ionic immigration and redox during RS process.On the other hand,graphene sensor also monitors the device’s working states,which can be divided into start-up,proper-working and over-load states.Subsequently,through high resolution TEM imaging,conductive filaments（CFs）were found in the Si O₂ layer,which indicates that RS effect in Ag/Si O₂ structure is based on the formation/rupture of silver CFs.Moreover,because of the nano-sized and crystalline features of the CFs,quantum conductance effect and its gate tunability were observed in this device.These results provide us detailed information to understand RS mechanism and paved the way for further development in self-monitored electronics.（2）To investigate RS effect in Layered Double Hydroxide（LDH）,we fabricated LDH devices based on graphene electrodes.Through electrical measurements,we found that LDH shows unipolar RS behavior accompanied with quantum conductance effect.These results indicate RS effect in LDH is based on the ionic immigration and formation/rupture of CFs.This concept was further confirmed by the C-AFM imaging,where nano-sized CFs were directly observed.Consider the simple structure,low cost,high on/off ratio（>10⁶）and high endurance of LDH based RS device,we believe it will have potential application in on-chip electronics.（3）Electrical measurements and Raman characterizations were used to comprehensively investigate charge density wave（CDW）phase transition and RS effect in TaS₂.These results suggest that CDW phase transition in TaS₂ is resulted from the lattice distortion and rearrangement of conductive electrons.This phase transition process is accompanied with distinct RS effect and can be effectively modulated by temperature,electric field and light.Moreover,electric field induced CDW phase transition in TaS₂ shows non-volatile RS behavior with multiple resistance states,indicating practical application in logic calculation and multi-level information storage.（4）We proposed the concept of thermal gate effect and systematical characterized the performance of TaS₂ thermal gate transistor.This newly designed transistor is based on the manipulation of CDW phases and resistance through local joule heat.Experimental and simulating results show that the thermal coupling between the thermal gate and TaS₂ channel dominates the performance of this transistor,and a vertical structure would greatly improve this thermal coupling process,where a sub-microsecond response speed and a MHz cut-off frequency have been achieved.Therefore,this conceptional thermal gate transistor may have potential application in developing next generation on-chip electronics.