Research On The Regulation Of HfO_x-based Analog Memristive Devices

With the increase of the frequency of information interaction and the advent of the era of artificial intelligence,the storage and computation of data needs a more efficient and fast method.Memristors with its excellent behavior as high speed,low power consumption,high intergration and CMOS process compatibility is expected to be the next generation of memory devices,as well as play a brilliant role in Analog In-memory Computing and artificial synaptic devices.The HfO_x-based memristor has been widely studied as a synapse-like device in neural network computation due to its excellent analog resistance switching performance.Ideal artificial synaptic devices need to have the advantages of high linearity,low variation and large analog switching window.Therefore,it is of great significance to explore a new model to realize gradual SET/RESET process while increasing the window of analog switching based on the mechanism of oxygen vacancy conductive filaments.Based on the methods of size effect control and homo-junction interface control,this paper explores the oxygen vacancy distribution and conductive filament evolution mechanism of reactive sputtering HfO_x memristor under these two ways,and further improves the analog switching characteristics through size matching,film composition matching and thickness matching,and lays the foundation for the device for neuromorphic computing.The main research contents of this article are as follows:(1)Research on the analog switching behavior of HfO_x-based memristor on size effect control.The HfO_x film with certain film defects of the same preparation process and thickness is used as the resistance switching layer.By changing the size of the device,the effect of size effect on the resistive switching behavior was further studied.By analyzing the conduction mechanism,a suitable device size with the potential for analog resistive performance is selected,and the DC simulation behavior and pulse simulation behavior of the device are further characterized,which proves a improved analog resistive performance by the size effect.(2)Study on analog switching behavior of HfO_x-based memristor on interface regulation of homogeneous junction.The structure of homogeneous junction device is formed by applying the HfO_y layer which y is close to the standard stoichiometric ratio on the HfO_x film with high oxygen vacancy content.Compared with the single-layer device,the DC resistive behavior of the device is more analogue and the swiching window is enlarged.Furthermore,analog switching behavior with high speed,large window and low variation is realized by pulse training.Based on the analysis of device structure and memristive behavior,the analog resistive switching model of“oxygen vacancy exchange between primary and secondary conducting filaments”is presented,and the improvement of analog behavior of the device by the interface regulation of homogeneous junction is expounded.