A Design And Simulation Of Displacement Transducer Based On Meso-piezoresistive Effect

With the rapid development of MBE(Molecular Beam Epitaxy)and NEMS (Nano-Electromechanical System)fabrication technology, various superlattice quantum well devices have been fabricated today. When the critical dimension of device approaches nanometer magnitude, several effects will be appeared including the quantum effect. So, these novel devices will appear new characteristics and good performances, because of the dimensional effect. In this thesis, we study the micro-displacement transducer based on Meso-piezoresistance Effect used in GaAs superlattice semiconductor thin films. The Meso-piezoresistance Effect can be defined as following: Once a mechanical signal is applied for the double-barrier resonant tunneling(DBRT) structure, the DBRT will experience the induced strain, which will come into being the built-in electric field in the thin films. The strain and built-in electric field will lead to the change of electronic energy states(such as a shift),which will influence on the value of the tunneling current. Thus, a weak mechanical signal can be converted into a strong tunneling current signal in principle through the four physical processes stated above.This thesis introduced work principle and structure of the piezoresistive micro-displacement transducer those based on GaAs material. It used Matlab software to calculate some parameters of the DBRT core component, used Ansys software to analyze the displacement,strain and intrinsic frequency of the elasticity beam. It finally calculated the sensor input and output characteristics and sensitivity, and compared with classic piezoresistive displacement sensor.The main research contents below:(1) Calculated and ratiocinated the DBRT structure's transmission coefficient and tunneling current.(2) DBRT structure, the calculation of the strain on the tunneling current, analyzes the impact of the piezoresistive effect.(3) Calculated the characters of the input and output and natural frequency of the equal sectional beam and the equal strength beam.(4) Used Ansys software to simulate the two kinds of elastic beam's strain and the inherent frequency, selected the appropriate location to affix strain gages, calculated its input/output relationship and sensitivity, and compared with the similar sensors.This thesis theoretically proved meso- piezoresistive effect principle can improve the sensitivity of the sensor, and provided a idea for design of new sensor.