Resistive Switching Behaviors And Synaptic Functions Realized In SrTiO₃ Memristive Devices

In recent years,the memristor shows high speed,low power consumption,simple structure,simple manufacturing process and other advantages.Memristor is well-performing resistive random-access memory that has the potential to be next generation of memory.In addition,memristor successfully emulates biological synapse function and will soon become a key device for construction of artificial neural networks in the future.At present,memristor has become a research hotspot in the fields of materials,information and artificial intelligence.However,there are still some problems in the research of memristor.For example,the discussion on the mechanism of resistive switching is still controversy,and it is difficult to emulate complex synaptic functions using memristor,the performance of the device still needs to be improved.Therefore,SrTiO₃ devices were prepared to study the performance of SrTiO₃ memristors and explore the mechanism of resistive switching;The interface of SrTiO₃ memristor was controlled to regulate the time characteristics of the low resistance state of the device and emulate complex synaptic plasticity;Pt/G/SrTiO₃memristors were prepared to improve the performance of the device.The main research contents are as follows:The SrTiO₃ devices were fabricated by pulsed laser deposition and magnetron sputtering.The effects of different electrodes,temperature,humidity and vacuum on the resistive switching were studied in detail.In addition,it has been found that easily oxidized electrodes and adding easily oxidized metal particles in inert metal electrodes affect the retention of the device.Continuously tunable forgetting rate of the devices was realized in SrTiO₃ devices by introducing easily oxidized metal into the inert electrode to design the electrode/oxide interface.Using this unique feature,biologically important BCM learning rule of synapse with tunable sliding frequency threshold was emulated.Using TEM,XPS and other testing methods,the microstructure of the interface of the devices with mixed metal electrodes and physical mechanism of tunable forgetting rate were studied in detail.The Pt/G/SrTiO₃ memristors were prepared to improve the retention performance using the blocking effect of graphene on ion migration.In this thesis,the systemic resistive switching mechanism of SrTiO₃ based memristor is studied,and versatile synaptic functions were emulated based on the characteristics of the device.These results are important for the development of memristive synaptic devices.