Design and Investigation of Pressure Sensor Based on Charge Plasma Silicon NWFET with Cylindrical Gate Diaphragm

摘要

In this paper, we demonstrate a nanoelectro-mechanical system (NEMS) diaphragm pressure sensor based on dopingless charge plasma-gate all around (GAA) silicon Nanowire Field Effect Transistor (NWFET). By incorporating the advantages of GAA configuration i.e. better electrostatics and reduced short channel effects (SCEs) with those of dopingless configurations like reduced random dopant fluctuations (RDFs) give rise to an ultrasensitive pressure sensor with higher reliability. The surrounded gate in GAA behaves as the diaphragm. The applied pressure on the diaphragm bends the diaphragm that changes the metal-dielectric thickness of oxide layer that in turn affects the electrical characteristics of the device. The diaphragm bendings considered are 1, 1.5, 2 and 2.5 nm. Various device characteristics including potential, energy band diagrams, electron-hole concentrations, Ion, Ion/Ioff ratio etc. are evaluated which can be used as performance parameters of the proposed structure. Further investigation of the device's design parameters for optimized sensor designing viz. dielectric material of spacer and length of the spacer is carried out. Results reveal that this ultrasensitive pressure sensor with lower SCEs shows higher reliability and yield comparatively higher sensitivity towards applied low pressures as low as 0.73 pN/nm(2). The drain current could be increased by using high-k material at spacer (HfO2) and also spacer length around 10 nm provides better switching. Thus, with ease of fabrication, this sensor could be used in low-pressure sensing applications for the biomedical field.