Analysis of NaCl Electrolyte Based SOI-ISFET pH Sensor

Abstract

In this paper, the analysis on the characteristic of the Silicon-on-Insulator Ion-Sensitive Field Effect Transistor (SOI-ISFET) pH Sensor has been carried out. NaCl is used as an electrolyte to sense the change in pH value. The analysis includes DC analysis which is modeled using Poisson/Boltzmann equations and frequency-dependent AC analysis which includes Poisson/Nernst/Planck–Poisson/Drift/Drift equations together with site binding charge model equations at the electrolyte and insulator interfaces. The simulation is carried out using ENBIOS-2D Lab tool provided by nanohub group. From the results, it is observed that with an increase in the pH value, the slope of the transfer curve decreases and the threshold voltage of the device increases. Also, the frequency-dependent performance of the device at pH value of 7 is analyzed and it is observed that the device becomes less sensitive at higher frequencies.