Study On Synthesis And Plasma Modification Of Zinc Oxide Nanowires

Zinc Oxide(ZnO)has broad application prospects in optical devices,electronic devices and photovoltaic devices,due to its excellent photoelectric properties.In addition,the zinc oxides(ZnO)based resistive random access memory(RRAM)can be prepared for transparent storage devices by using the large amounts of natural defects and well controlling them in ZnO.In the downsizing of electronic devices,nano-dimensional storage medium as building block of RRAM can greatly improve storage density.Therefore,it is important to study the ZnO nanowire(NW)based resistive switching characteristics.Plasma modification is one of the effective methods to improve the defects,but its effects on resistive switching of ZnO NWs have been rarely reported.Therefore,the ZnO nano wires were prepared by vapor deposition in this paper,and study the effects of preparation process and plasma modification on the properties of ZnO nanowires.The Ti/ZnO NW/Ti structure was prepared to study the effect of plasma modification on the resistance switching properties of ZnO nano wires.ZnO nanowires are of hexiagonal wurtzite structure and grow along c axis direction.Growth time extension has a promoting effect on the diameter,lengh and orientation of ZnO nanowires,but the homogeneity of samples become worse.The increase of Au thickness increases the diameter of ZnO nanowires,and improves the uniformity of samples.In addition,the increase of gas flow rate can reduce the diameter of ZnO nanowires,and damage the uniformity of samples.Plasma modification has remarkable effect on defects of ZnO nanowires.N2,O2 plasma modification reduces the defects and inhibits the green emission from ZnO nanowires.However,Ar plasma modification strengthens the green emission by introducing defects into ZnO NWs.The single ZnO nanowire exhibits reproducible bipolar switching behavior.The conduction in the low resistance state(LRS)is attributed to conductive filaments(mainly formed by the oxygen vacancy),while the conduction in the high resistance state(HRS)is dominated by the space-charge-limited mechanism(SCLC).After the N2 plasma or O2 plasma treatment,the resistive performance of ZnO nanowires becomes poor.However,for the argon plasma treated samples,the bombardment effects of argon plasma introduce the oxygen vacancies in ZnO,the repeatability and stability of resistive switchings could be improved since the stochastic switchinges could be suppressed and averaged out by additionally introduced oxygen vacancies.In addition,the appropriate increase of oxygen vacancy enhances selectivity of electron hopping transport between the vacancies.Thereby the electron hopping distance could be further refined to realize the multistate storage of single ZnO nanowire based memory.