20August2019

Nano-Micro Letters

Micro-Accelerometer Based on Vertically Movable Gate Field Effect Transistor

Heung Seok Kang1, Kang-Hee Lee1, Dong-Youk Yang2, Byoung Hee You3, and In-Hyouk Song3,*

Abstract
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Nano-Micro Letters, , Volume 7, Issue 3, pp 282-290

First Online: 06 May 2015 (Article)

DOI:10.1007/s40820-015-0041-9

 

Abstract

 


Schematic of the vertically movable gate FET accelerometer (unit: m). Note: Figure is not drawn to scale.

 

A vertically movable gate field effect transistor (VMGFET) is proposed and demonstrated for a micro-accelerometer application. The VMGFET using air gap as an insulator layer allows gate moving on the substrate vertically by external forces. Finite element analysis is used to simulate mechanical behaviors of the designed structure. For the simulation, the ground acceleration spectrum of the 1952 Kern County Earthquake is employed to investigate the structural integrity of the sensor in vibration. Based on the simulation, a prototype VMGFET accelerometer is fabricated from silicon on insulator wafer. According to current-voltage characteristics of the prototype VMGFET, the threshold voltage is measured of 2.32 V, which determines the effective charge density and the mutual transconductance of 1.545×10-8 C cm-2 and 6.59 mA V-1, respectively. The device sensitivity is of 9.36-9.42 mV g-1 in the low frequency and the first natural frequency is found to be 1230 Hz. The profile smoothness of the sensed signal is in 3 dB range up to 1 kHz.

Keywords

MEMS; Micro-accelerometer; Suspended gate FET; Vertically movable gate FET; VMGFET

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