Research Of ZnO Nanowires Young’s Modulus In Air

ZnO nanowire is a kind of good piezoelectric material,and one of its important applications is to convert mechanical energy into electrical energy for powering nanoscale system.The young’s modulus of the nanowires in the power generation efficiency and the size of the force range plays an important influence.Research of ZnO nanowires Young’s modulus is mainly concentrated on the experiment measuring Young’s modulus and its variation with the size.Most researchers measures on ZnO Young’s modulus of nanowire in a vacuum environment by scanning electron microscopy and transmission electron microscopy.In this paper,we design an experiment in the atmospheric environment by noncontact mode of atomic force microscopy measuring ZnO nanowire resonant frequency.According to the experimental results we make the simulation analysis of Young’s modulus of surface and rule of radial variation of ZnO nanowires in the air.Contrasting value of vacuum with the value of air.About the experimental device,plating a layer of gold film on the silicon substrate as ZnO catalyst for the growth of nanowires.Growing ZnO nanowires in circular wafer substrate by the high temperature tube furnace with gas liquid solid(VLS)growth method.Through a photolight processes and two thermal evaporation method on substrate.We get the on strips parallel gold electrode at the end.A method for measuring the resonance frequency of ZnO nanowires in atmospheric environment is proposed by using the noncontact mode of atomic force microscopy.The nanowire is vibrated by self-made parallel microelectrodes with transverse alternating electric field,and the distance between the tip and the nanowires in the range of molecular force.The tip is synchronized with the nanowire by molecular force.By gradually changing the frequency of the alternating electric field,the nanowires are subjected to the continuous change of frequency.The position of the probe can be identified by photoelectric sensor,so that the resonance of nanowires can be determined by judging the surge of photoelectric sensor signal,and the resonant frequency of nanowires can be obtained.The relationship between resonance frequency and geometric size from the Euler Bernoulli beam vibration theory shows that the young’s modulus of seven ZnO nanowires with different diameters is not equal,which are not equal to ZnO bulk material value,and the difference between the seven groups is also large.In the view of this phenomenon,from the perspective of crystal growth principle,the nanowire size is nanoscale,so the thickness of nanowire growth boundary has great influence on the overall performance of nanowires.With the application of multiphysical field coupling simulation,The vibration of a nanowire core-shell model considering the effect of thermal viscous damping in the air and atmospheric pressure environment is simulated following the process of experiment,the the shell young’s modulus of nanowire and the whole Young’s modulus change rule in air are obtained.Finally,we get the young’s modulus of the ZnO nanowire shell in the atmosphere that is 336.71+55GPa,which is about 37% higher than that of the previous study.The overall Young’s modulus of nanowires in the atmosphere is faster than that in vacuum as the diameter decreases.