Modal Analysis and Design of a Vertically Movable Gate Field Effect Transistor (VMGFET) Proposed for Low-Frequency Sensing Applications

Abstract

The objective of this study is to design and optimize a vertically movable gate field effect transistor (VMGFET) - suitable for low-frequency, high-sensitivity applications - with an emphasis on modal analysis of the suspended gate structure, optimization of mesh density within the employed finite element analysis software, and optimization of the moveable gate dimensions given its relationship with fabrication complexity and the structure’s resonant frequencies. The methods of design, optimization, and analysis were carried out with COMSOL Multiphysics 4.2a under the assumption of no damping with free vibrations. The results indicate optimal dimensions of the suspended gate structure - given constraints on size, resonance, and fabrication complexity - which suggest a beam thickness of 3 µm and a beam width of 15 µm, yielding an upper limit of input force frequencies near 2 kHz.