Modeling and simulation of ion-sensitive field-effect transistor using TCAD methodology

Ion Sensitive Field Effect Transistor (ISFET) is a popular potentiometric sensor which can be used for chemical and biochemical sensing. This paper presents the modeling of the electrolyte-insulator-semiconductor structure of ISFET using Silvaco TCAD tool. The electrolyte region along with reference electrode has been modeled as a semiconductor with suitable parameters calculated analytically. Silicon nitride is used as the sensing film and it is observed that a sensitivity of 57.143 mV/pH is obtained for pH sensing application. The effect of using different sensing film thicknesses has also been studied and presented. It is observed that the sensitivity of the device reduces as the sensing film thickness is increased.