Analytical Physical Model for Electrolyte Gated Organic Field Effect Transistors in the Helmholtz Approximation

Abstract

The analytical physical modeling of undoped electrolyte gated organic field effect transistors (EGOFETs) in the Helmholtz approximation is presented. A compact analytical model for the current–voltage (I–V) characteristics, which includes the effects of the access series resistance, has been derived and validated by means of 2D finite element numerical calculations. The model describes all operating regimes continuously (subthreshold, linear, and saturation regimes), covers channel lengths down to a few micrometres and only includes physical device parameters. From the model, analytical expressions have been proposed for all the phenomenological parameters (e.g., capacitance, threshold voltage, sub-threshold slope voltage, and sub-threshold capacitance) appearing in the commonly used ideal FET model. The derived analytical physical model provides a simple and quantitative way to analyze the electrical characteristics of EGOFETs and EGOFET biosensors beyond the use of the oversimplified and phenomenological ideal FET model.