Fabrication And Mechanism Study Of Halide Perovskite Based Selector Device

Due to the simple structure,excellent scalability characteristics,fast speed of read and write,resistive random access memory（RRAM）occupied an increasingly important position in the research of the next generation of non-volatile memory.Among the numerous resistance-switching materials,halide perovskite materials own fast migration of ions,which makes it be applied in resistance switching memory with high speed and low power consumption.Due to its simple preparation process,integration on flexible substrates,and photo-electric tenability,halide perovskite based resistive switching memory has attracted extensive attention in recent years.Lately,the work of halide perovskite based resistive switching memory array has ever been reported for flexible wereable application.In these reports,crosspoint structure was used for the integration of these arrays due to its simple structure,high integration and low cost.However,there is also a challenge in corsspoint structure,which is the sneak path current problem.This problem can cause the memory states in the array to be misread.To solve this problem,a non-linear selector device is usually connected in series with the resistive switching memory in the array.To integrate with halide perovskite based resistive memory device and make an array,the halide perovskite based selector would be one of a good choices.However,there have been no reports of the halide perovskite based selector up to now.In this thesis,halide perovskite based selector was designed,fabricated and characterized with two different top electrode materials（Ag and Au）.Their mechanisms were also analyzed and studied.Finally,halide perovskite based selector and resistance switching memory was in series and characterized.It can be found that the halide perovskite based selector can prevent the sneak path current.The main research contents are as follows:1.The threshold switching selector with Ag/Cs_x(MA_0.17FA_0.83)_（100-x）Pb(I_0.83Br_0.17)₃/ITO structure was fabricated.It was found that bidirectional threshold switching characteristics was shown after appropriate electrical stimulation on the virgin device under the compliance current conditions of 0.01 mA,0.1 mA,and 1 mA.When the compliance current is 1 mA,which is also the on-state current,the device was shown higher gating ratio（positive direction:>2×10³;negative direction:>5×10²）,faster switching speed（positive turn-on:160 ns;positive turn-off:425 ns;negative turn-on:170 ns;negative turn-off:635 ns）,better electrical stability（over 100DC sweeps）,and good device uniformity.It was also studied that the formation and dissolution fracture of the conductive filament composed of Ag element in the perovskite layer dominates the switching of the selector.2.The threshold switching device of Au/Cs_x(MA_0.17FA_0.83)_（100-x）Pb(I_0.83Br_0.17)₃/ITO structure was fabricated.It was found that the device can achieve a threshold switching characteristics under the compliance current conditions of 0.01 mA,0.1 mA,and 1 mA in the N₂ environment.When the on-state current is 1 mA,a higher gating ratio（positive direction:>10⁶;negative direction:>2×10⁵）and good electrical stability（over 60 DC sweeps）were also achieved.The mechanism of the threshold switching characteristics of the device was also explored.Under the small electric field,several multi-vacancy islands composed of discrete halide vacancies could be formed in the perovskite layer.It might be tunneling junctions between adjacent halide vacant groups.When the voltage applied was large enough,carriers can pass through the tunneling junction,thereby showing conductance.3.The series characteristics of halide perovskite based selector device and resistance switching device were also tested to verify that the selector can suppress the sneak path current.The flexible halide perovskite based selector were also fabricated with excellent mechanical flexibility,indicating that halide perovskite material could be potentinally applied in future wearable devices.