Study Of Memristor And Photoelectric Response Based On Multiphase Rhenium Disulfide

Memory technology is an important part of China’s strategic emerging industry in tegrated circuit.As one of the new information storage technologies,memristor has a wide application integrated optics,such as the next generation optoelectronic informati on memory and artificial vision system.Here we utilize crystal phase engineering,to prepare heterophase sulfide rhenium ReS₂.This heterophase ReS₂shows different performance compared to single phase structure and could meet different functional requirements of different electronic devices.In addition,we studied the detailed atomic structure of ReS₂,the migration of sulphur vacancy and phase transition between Td and Tc phase in system.We prepare heterophase ReS₂nanosheets by phase engineering to gain special characteristics.And then,we also prepared ferroelectric tunneling junction,lateral memristor and light-tunable memristor based on the heterophase ReS₂nanosheets.The detailed results are described as follows:（1）We have prepared lateral Ag/ReS₂/Ag memristor based on heterophase ReS₂.These memristors show high switching ratio（＞200）,practical resistance in both low and high resistance states（HRS:～10 n A,LRS:～5μA）,low set field(<10³V/cm,V_set～1.22 V),low energy consuming(～100 W cm^-2).In situ Raman scattering was used to characterize the T_Cphase distribution in different resistance states.The Raman shift mapping clearly shows that the content of Tc phase increased obviously in HRS than LRS.Therefore,this lateral resistance switching mostly originates from the phase transition between Tc and Td.In addition,ferroelectric tunnel junction was prepared by using the out-of-plane ferroelectric based on heterophase ReS₂.Under the set voltage of±5 V,the electric dipole moments in heterophase ReS₂will be arranged in one directional way.This arrangement of dipoles results in quite difference of potential between the upper and lower surfaces of ReS₂.This difference thus causes the tunneling resistance effect.According to the different directions of the electric dipole moments,different resistance states will be generated.（2）It is found that the photoresponse of lateral heterophase memristors with different concentrations of Tc/Td is different.When the concentration of Tc/Td is greater than about 1/4,the memristor performance is better.It is found that the effect of light on each resistance state of lateral heterophase ReS₂memristor is very small（<10）.When the concentration of Tc/Td is less than 1/4,the performance of the memristor is poor,and the influence of laser on the high resistance state is also less than 10 times.However,when the memristor is in the low resistance state,the resistance of the memristor increases rapidly by two orders of magnitude and lasts for more than 1 h under the effect of light.The results show that the device is most sensitive to 532 nm,and the response becomes more obvious with the increase of laser intensity.Only under the negative voltage pulse,the memristor could enter into the low resistance state again.By theoretical calculation and XPS,it is found that when the ratio of Tc/Td is less than 1/4,the sulfur vacancy concentration in rhenium sulfide is not enough to promote the transformation of Td phase into Tc phase,which needs the assistance of laser.Therefore,the low resistance state can be transformed into high resistance state under the action of laser.The change of resistance state controlled by laser and voltage pulse can not only be used in special photosensitive devices,but also lay a solid theoretical and experimental foundation for the application of memristor in artificial brain,electronic eye and other medical life structures.