| With the rapid development of emerging technologies such as artificial intelligence,big data and 5G,traditional computers based on "von Neumann architecture" are facing problems such as memory wall and power wall,which are difficult to meet the exponential growth of computing demands.The realization of brain-like memory is an important way to improve computing power.Among the new memory devices,memristor is the key to realize this improvement.The memristor has the advantages of non-volatile storage,low power consumption,size miniaturization,CMOS compatibility,and resistive state modulation under external excitation for neuromorphic applications.In addition,the high and low resistance states of the memristor represent 1 and 0 respectively,which can be used for binary storage.However,at present,the researches of memristor are mostly limited to the realization of synaptic performance,rather than the application progress in Boolean logic operations,especially in the realization of 16 complete Boolean logic operations on a single memristor device,reducing the size of the logic gate and other aspects still need to be further explored.This paper focuses on the following research:The Ag/Ta_xO_y/ITO memristor device was constructed and optimized.Oxygen partial pressure of electrode material and functional layer Ta_xO_y was optimized.The results of XPS and electrical tests show that the operating voltage of the device decreases and the switching ratio increases with the increase of the metal electrode participating in the resistance behavior.At the same electrode,with the increase of oxygen content of Ta_xO_y,the switching ratio of the device increases and tends to form,which is not conducive to the application of memory.In this paper,Ag/Ta_xO_y/ITO memristor devices were constructed by using Ta_xO_y with 10%oxygen content on Ag electrode.On this basis,the I-V characteristics of the device are fitted with double logarithms.From the perspective of ion dynamics,it is revealed that the high resistance state of the device is SCLC mechanism,the low resistance state is Ohmic transmission mechanism,and the reversal of the resistance state depends on the dual action of Ag+and oxygen vacancy.The resistivity behavior of conductive filaments was further verified by cross-section characterization with high resolution transmission electron microscopy.Synaptic performance was investigated based on Ag/Ta_xO_y/ITO memristor.The results showed that the modulating ability of double pulse was up to 63.27%,and the modulating ability of synaptic plasticity was up to 165%,which indicated that the memsteric structure was a good neuromorphic device.A complete 16 Boolean logic operations are realized in a single Ag/Ta_xO_y/ITO memristor.To this end,this paper introduced two control quantities,"Initialization W"and "Writing C",to control writing data and initial stored data to carry out Boolean logic operations,defined the high and low resistance states of the memristor as binary logic 0 and 1,and read the logical operation results inside the excitation pulse.Comparing the experimental results with the truth table,it is shown that the Ag/Ta_xO_y/ITO memristor device prepared in this paper can correctly run 16 Boolean logic operations,which proves that the memristor not only has good synaptic characteristics,but also has in-situ storage and operation functions,laying a foundation for the realization of a computer integrating storage and computing.This work explores the feasibility of data computation with neuromorphic memory devices and lays a foundation for solving von Neumann’s bottleneck. |
PDF Full Text Request