Performance analysis of 3D flexure FET with meandering gate for higher sensitivity

Abstract

This paper is focused on utilizing the nonlinear electromechanical coupling to overcome the fundamental sensitivity limits of classical electrical or mechanical sensors. The stiffness of the suspended gate of Flexure-FET changes with the capture of the target molecules and the corresponding change in the gate shape or deflection is reflected in the drain current of FET. This paper deals with the design and simulation of Flexure Gate Field Effect Transistor (Flexure-FET) and the comparative analysis of the different structures of gate using gold (Au) and poly-silicon and presents the investigation of pull-in voltage of the gate and the change in capacitance in between the gate and the channel due to the actuation. The effect of change in gate thickness is reflected in the drain current characteristics of FET and the corresponding ratio of drain current is investigated for higher sensitivity. The simulation has been carried out for fixed-fixed suspended gate with non-uniform meander and both end clamped without meander configurations. The substrate and dielectric used are p-type silicon and SiO2 respectively. The Flexure FET is designed using the commercially available MEMS simulator tool COMSOL 4.4 which uses Finite Element Method (FEM) for the electrical, mechanical and the electromechanical analysis. The Von Mises stress analysis of all the structure is also investigated.