TCAD-Based Simulation Method for the Electrolyte–Insulator–Semiconductor Field-Effect Transistor

A simulation method for the electrolyte-insulator-semiconductor field-effect transistor (EISFET)-type sensor is proposed based on a well-established commercialized semiconductor 3-D technology computer-aided design simulator. The proposed method relies on the fact that an electrolyte can be described using a modified intrinsic semiconductor material because of the similarity between the electrolyte and the intrinsic semiconductor. The electrical double layer of the electrolyte is characterized in the simulation using the Gouy-Chapman-Stern model. Using the proposed simulation method, we extract the Debye lengths depending on phosphate buffered saline solutions with various concentrations and demonstrate that it is possible to simulate the screening effect. Furthermore, we investigate the responses of the EISFET-type silicon nanowire pH sensor based on our simulation method, which shows good agreement with the reported Nernst limit value.