A silicon nanowire ion-sensitive field-effect transistor with elementary charge sensitivity

We investigate the mechanisms responsible for the low-frequency noise in liquid-gated nanoscale silicon nanowire field-effect transistors (SiNW-FETs) and show that the charge-noise level is lower than elementary charge. Our measurements also show that ionic strength of the surrounding electrolyte has a minimal effect on the overall noise. Dielectric polarization noise seems to be at the origin of the $1/f$ noise in our devices. The estimated spectral density of charge noise $Sq=1.6×10−2e/Hz1/2$ at 10 Hz opens the door to metrological studies with these SiNW-FETs for the electrical detection of a small number of molecules.