Design And Preparation Of Memristor Materials And Devices With Multilayer Film Structure

Memristors are considered as the basic element of the fourth circuit and the next generation of non-volatile memory devices.At the same time,it can realize non-volatile state logic operations and brain-like neuromorphic calculations,which is of great significance in improving computing performance and in deepening artificial intelligence.This thesis first introduces the development history and research status of memristors,and then introduces the structure design,electrical property testing,and material characterization of memristors.The preparation,electrical properties,material characterization,resistance change mechanism,and application of several memristors with multilayer structures using cerium oxide as the basic functional layer material were discussed.The main research contents of this thesis are as follows:?1?Ag/Ti/CeO₂/Pt devices can exhibit both bipolar resistive switching?BRS?and unipolar resistive switching?URS?behavior at room temperature.In BRS,the device had a low Set voltage?about 0.3 V?and Reset voltage?about-0.1 V?-0.3V?,no Forming process was needed,the limited current was 1 mA.After performing the voltage scan of the device for 120 cycles,the device performance was found stable,these properties are beneficial for the application.We analyzed its double logarithmic I-V characteristic curves,and combined with the observation by transmission electron microscopy,we found that during bipolar resistance switching,the device's conduction mechanism was mainly electrochemical metallization mechanism?ECM?.When we accelerated the scanning speed and increased the limiting current,the unipolar resistance switching phenomenon was observed.The device's conductive mechanism was mainly thermochemical mechanism?TCM?.This shows that by changing the scanning speed and the limiting current,the resistive characteristics of the device would also change.In addition,we also discussed the failure mechanism of the devices and the change in the porperties of the device after a long period of storage.?2?Pt/Ti/AlO_x/CeO_x/Pt showed BRS behavior at room temperature.This device needed no Forming process and had low resistance switching voltage?0.6V?-1 V?with a current compliance of 8 mA.At the same time,we also observed a sudden change in the set process and a gradual change in the reset process,and multi-resistance values were obtained when different negative scanning voltages were applied.The device resistance changed abruptly when the positive voltage was about 0.6 V,this is beneficial for their application in the multi-value storage.At the same time,in the negative voltage section,we observed a negative differential effect in the voltage-current characteristic curve.After that,we tested the cycle characteristics of the device,and the good high resistance and low resistance retention were proved.We further analyzed the double logarithmic I-V characteristic curves of the devices,and we further proposed the resistance switching mechanism of the device and found that the formation and fracture of oxygen vacancy conductive filaments dominated the process.?3?We prepared the memristor?Pt/AlO_x/CeO_x/Pt?composed of two different media which could realize the complementary resistive switches?CRS?,this simplifies the manufacturing process of CRS.The device had a more prominent high/low resistance state ratio,which is convenient for detecting and for the peripheral circuit design.However,the stability of the device needs to be further improved.We deduce that depletion and migration of oxygen vacancies are the CRS resistance mechanism of the device under different voltages and in different materials.This double-layer structure provides new ways for the development of CRS devices.Most of the devices prepared are in a high-impedance state,which greatly reduces power consumption.The devices not only have the storage function but also can implement complete logic operations,they have great advantages in the integration of the storage and computing.