Detection And Control Of Vibration Characteristics Of Carbon Nanotubes Under Scanning Electron Microscope

As a device for generating resonant frequency,Resonators are applied to almost all electronic products and components that involve frequency emission and reception.With the rapid development of nano science and technology,the research of resonant devices based on nano-electromechanical systems(NEMS)is attracting wide attention.Compared to the traditional MEMS resonant device,the NEMS resonator has nanometer size,resonant frequency up to GHz and high Q value(mechanical quality factor),which is expected to replace quartz crystal resonator and has a very bright application prospect.In this paper,carbon nanotubes are used as resonators to control the resonant frequency and quality factor of carbon nanotubes as the main purpose.First,the vibration model of carbon nanotube was established on the basis of the vibration of the carbon nanotube excited by static electricity,and the vibration platform of the carbon nanotube was built in the scanning electron microscope with the aid of the micro nano manipulator.Secondly,a vibration characteristic detection method based on signal generator and scanning electron microscope is designed.Finally,by adjusting the length of carbon nanotubes and adding mass at the free end of the carbon nanotubes,we can control the vibration frequency and quality factor of carbon nanotubes.The main contents of this paper are as follows:(1)Based on the vibration mode of the carbon nanotube cantilever beam,the vibration model of the carbon nanotube was established.On this basis,the motion equation of the vibration of the carbon nanotube was obtained.The main performance parameters and characteristics of the carbon nanotube were studied.The effect of the effective mass of carbon nanotube and the characteristic parameters on the resonance frequency and the quality factor Q of the carbon nanotube was obtained.(2)The vibration platform of the carbon nanotube was built with the scanning electron microscope and the micro nano manipulator.First,a carbon nanotube is picked up by the carbon nanotube pickup platform.Secondly,the carbon nanotube and the tungsten needle are installed on two micrometer operating devices which are perpendicular to each other,and a signal generator is used as a signal source to stimulate the vibration of carbon nanotubes.Finally,the resonant frequency of carbon nanotubes is obtained by simulation.(3)A vibration frequency and amplitude detection method based on signal generator scanning frequency and scanning electron microscope two times electronic imaging is designed.The vibration frequency of the carbon nanotube is obtained by the output frequency of the signal generator and the vibration image of the carbon nanotube is obtained by the two electron imaging of the scanning electron microscope and the amplitude of the carbon nanotube is measured.Finally,the collected multi group amplitude and frequency data is plotted into the amplitude frequency curve by Origin software,and the resonant frequency and the quality factor Q are calculated.(4)Two control methods for vibration characteristics are designed.The first method is to control the vibration characteristics of carbon nanotubes by adjusting the length of carbon nanotubes.In the experiment,carbon nanotubes with different lengths were obtained by changing picking strategy and irradiating by electron beam.The second method is to control the vibration characteristics by growing Pt nanowires through field emission.For the two control methods,theoretical analysis and simulation were carried out first,and finally verified by experiments.