Fabrication And Properties Of TaO_x Based Memristor

With the continuous development of science and technology,the traditional Flash memory can not meet the needs of people,and the memory resistor(RRAM)with its small size,low power consumption,non-volatile storage,fast read-write speed and other characteristics is considered to have great potential to replace Flash memory.Memristor integrates memory and logic operation,which can break through the traditional von Neumann bottleneck.In addition,memristor can also be applied to biological neural networks,because its plasticity and memory are very similar to biological synapses,and it is the most suitable device to simulate the behavior of biological synapses.In this paper,three kinds of TaOx dielectric thin films with different oxygen content were prepared by magnetron sputtering,and two kinds of memristors with Cu/TaOx/p++-Si and Ag/TaOx/p++-Si structures were designed and constructed by combining with lithography process.Based on the "analog resistance switching" potential of Ag/TaOx/p++-Si memristor,the device performance was further optimized,and Ag/TaOx:Ag/p++-Si memories with "analog resistance switching" behavior were prepared.Finally,in order to fabricate a memristor with synaptic properties,the second resistive layer Hf Ox and Al Ox were inserted,Ag/TaOx:Ag/Hf Ox/p++-Si and Ag/TaOx:Ag/Al Ox/p++-Si double resistive layer memristors were designed and prepared,and A number of memristive synaptic functions were tested on Ag/TaOx:Ag/Al Ox/p++-Si memristors with better synaptic performance.The main research results of this paper are as follows:(1)Cu/TaOx/p++-Si memristor is a kind of nonvolatile "digital resistance switch",its switch is relatively large,but the repeatability is not high.Ag/TaOx/p++-Si memristor is a kind of nonvolatile resistance switch,which has the potential to become an "analog resistance switch";with the increase of the number of cycles,its HRS current gradually increases,and the LRS current is relatively stable,resulting in a "Three-stage" decrease in the switch ratio,and finally less than 102,indicating that the conductive channel formed inside the device is not stable.(2)The Ag/TaOx:Ag/p++-Si memristor has a gradual Set and Reset process,showing the characteristics of "analog resistance switching".In 100 cycles,compared with the Ag/TaOx/p++-Si memristor,the HRS current and LRS current distribution of the Ag/TaOx:Ag/p++-Si memristor are relatively stable during 100 cycles,but the switching ratio and Reset the voltage range is too small,which makes the resistance control range of the device not large and the reliability is not high.(3)Ag/TaOx:Ag/HfOx/p++-Si memristors work repeatedly and stably,HRS current and LRS current are distributed stably,and the On-Off ratio is stable at about 22,realizing continuous regulation of resistance in a small range.Ag/TaOx:Ag/AlOx/p++-Si the memristor achieves a switching ratio of more than 102 in 500 cycles,and obtains more stable HRS current and LRS current,Set voltage and Reset voltage,as well as a larger resistance regulation range;Ag/TaOx:Ag/AlOx/p++-Si memristor also simulates a number of biological synaptic behaviors,and successfully realizes a variety of synaptic functions,such as synaptic weight regulation,double pulse facilitation,pulse amplitude dependent plasticity,pulse width dependent plasticity,pulse frequency dependent plasticity and multilevel memory behavior.