Carbon Nanotube Resonator Dynamics Modeling And Simulation

Resonator is an electronic component which can be used to generate resonant frequency. It has been widely applied to all kinds of electronic devices related to frequency transmitting and receiving. NEMS resonator, based on nanoelectromechanical systems technology (NEMS), with the advantages of small size, high frequency, high Q value, low power consumption, easy to be integrated and many other benefits, has a very bright prospect and will surely replace the current quartz crystal resonator. This paper has conducted some research on the tunable carbon nanotube based on NEMS resonators, the main work including:(1) Conducted some theory study on the mechanical properties of electrostatic driving CNTs-based nanoelectromechanical resonator. The theoretical model of two typical structures—cantilever and doubly fixed CNTs nano-resonators were discussed, the influence of electrostatic force, elastic force and van der Waals force on its kinetic characteristics was also analyzed. Then, our theoretical study focused on failure voltage (or Pull-in Voltage), which is an important parameter for a tunable nanotube resonator. We also proposed the vibration governing equations of CNTs-based resonator. Finally, the principle of resonator detection circuit was investigated.(2) We established the coupled-field model of the resonator based on the finite element method using ANSYS package. Three numerical simulation methods have been taken into consideration to determine the failure voltage of the resonators, they are multi-field solver—MFS Single-Code Coupling method, TRANS 126 reduced order model method and the ROM144 element analysis method. The comparative analysis was carried out between the evaluated results and theoretically results. And base on the analysis results, we select an appropriate method with more computational efficiency and accuracy to solve the problems.(3) Modal analysis of cantilever and doubly clamped carbon nanotubes have been conducted to investigate the relationship between the geometrical variables of carbon nanotubes and its natural frequencies. This study can provide a guide on structural optimization and estimation of its working frequency range. Finally, we consider the DC bias voltage as a pre-stressed force acting on the nano-beam, and then take a pre-stressed harmonic response analysis to investigate the relationship between the DC bias voltage and the working frequency range.(4) Manufacturing technology of NEMS was investigated and two kinds of CNTs-based nanoelectromechanical resonator implementation methods were presented: NEMS by local CNT growth and integration method, NEMS by CNT assembly and integration method. At last, the fabrication process flow was proposed.In this study, a cantilever CNTs-based nanoelectromechanical resonator, with dimension of beam length L=500nm, beam radius R=10nm, and distance between nanotube and substrate H=100nm was presented. The tuning voltage range is 0～21.8v, the working frequency bandwidth is about 207.0MHz～302.0MHz. Moreover, A doubly clamped one, with dimension of L=1000nm, R=10nm, H=100nm, was also presented. The tuning voltage range is 0～46v, the working frequency bandwidth is about 474.8MHz～832.4MHz.