Gate-bias-controlled sensitivity and SNR enhancement in a nanowire FET pressure sensor

This work demonstrates a nanoelectromechanical pressure sensor based on a nanowire field-effect transistor (NWFET) sensing element. We report that the sensitivity of the pressure sensor can be enhanced up to four times when NWFET operates in subthreshold mode instead of inversion mode. The sensitivity enhancement is attributed to carrier confinement inside the nanowire channel which is obtained by gate bias tuning. In particular, the pressure sensitivity enhances from 0.019 to 0.079 (mA/A)/mmHg by changing the NWFET gate bias from 0.2 V (inversion region) to −0.2 V (subthreshold region). The low-frequency noise characteristics show the significant reduction in drain current noise for NWFET when biased in the subthreshold region, enhancing the signal-to-noise ratio (SNR) from 2 × 106 (inversion region) to 2.4 × 109 (subthreshold region). The result shows that the NWFET-based pressure sensor operates at a low bias with higher piezoresistance and can be used to measure low pressures with a high SNR./