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


Article Preview

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.



Edited by:

Huawu Liu, Yongxin Yang, Shijie Shen, Zhili Zhong, Laijiu Zheng and Peng Feng




J. Williams et al., "Modal Analysis and Design of a Vertically Movable Gate Field Effect Transistor (VMGFET) Proposed for Low-Frequency Sensing Applications", Applied Mechanics and Materials, Vols. 268-270, pp. 1538-1543, 2013

Online since:

December 2012




[1] T. Fujimori, Y. Hanaoka and H. Fukada: Above-IC integration of capacitive pressure sensor fabricated with CMOS interconnect processes, Proceedings of Microelectromechanical Systems 20, (2007).


[2] Y. Matsumoto, M. Nishimura, M. Matsuura and M. Ishida: Sensors and Actuators A Vol. 75 (1999), p.77.

[3] I. -H. Song and P.K. Ajmera: J. Microelectromech. Systems Vol. 18 (2009), p.208.

[4] L. -Y. Chen: Ph.D. dissertation (1995), Cornell University, Ithaca, NY.

[5] D. M. Edmans, A. Gutierrez, C. Cormeau, E. Maby and H. Kaufman: Micromachined accelerometer with a movable gate transistor sensing element, Proceedings SPIE 3224, (2000).


[6] J.W. Kang and K. Simonette: Surface micromachined multi-layer moving gate field effect transistor (MOGFET) pressure switch with integrated vacuum sealed cavity, Proceedings of IEEE MEMS (1999).


[7] K. Schranagl, M. Bogner, A. Fuchs, R. Winter and T. Doll: Sensors and Actuators B Vol. 57 (1999), p.35.

[8] E. Holzbecher and Hang Si: Accuracy Tests for COMSOL – and Delaunay Meshes, Proceedings of the COMSOL Conf. (2008).