Compact Modeling of pH-Sensitive FETs Based on Two-Dimensional Semiconductors

TL;DR

This paper introduces a physics-based, analytical model for pH-sensitive 2D material FETs, integrating electrostatics and carrier transport, compatible with circuit design tools, and validated against experimental data.

Contribution

It provides the first comprehensive, circuit-compatible analytical model for pH-sensitive 2D FETs, combining electrostatics and transport phenomena.

Findings

Excellent agreement with experimental data

Accurate prediction of drain current and threshold voltage shifts

Model applicable for circuit simulation of pH sensors

Abstract

We present a physics-based circuit-compatible model for pH-sensitive field-effect transistors based on two-dimensional (2D) materials. The electrostatics along the electrolyte-gated 2D-semiconductor stack is treated by solving the Poisson equation including the Site-Binding model and the Gouy-Chapman-Stern approach, while the carrier transport is described by the drift-diffusion theory. The proposed model is provided in an analytical form and then implemented in Verilog-A, making it compatible with standard technology computer-aided design tools employed for circuit simulation. The model is benchmarked against two experimental transition-metal-dichalcogenide (MoS2 and ReS2) based ion sensors, showing excellent agreement when predicting the drain current, threshold voltage shift, and current/voltage sensitivity measurements for different pH concentrations.