Evaluation of sensitivity in a vertically misaligned double-gate electrolyte-insulator-semiconductor extended source tunnel FET as pH sensor

Abstract

In this research, the primary objective is to investigate the impact of vertical gate misalignment on the source and drain regions of 30 nm. The double-gate Electrolyte-Insulated-Semiconductor extended-source Tunnel Field-Effect Transistor (ES-VTFET) is proposed for its potential application as a pH sensor. The gate electrode cannot be perfectly aligned with the channel due to fabrication tolerances, particularly in very short-channel structures. This study aims to introduce a vertical electrolyte Bio-TFET-based pH sensor capable of detecting pH changes in aqueous (electrolyte) solutions. The effect of variation in pH values on the electrical characteristics of the device such as drain current ($I_{DS}$), transconductance ($g_m$), voltage sensitivity ($S_V$) and current sensitivity ($S_I$) have been examined. It has been assumed that the electrolyte section is an intrinsic semiconductor material where electrons and holes signify mobile ions in aqueous solutions. The electrolyte region has an electrolyte dielectric constant of 78, an energy bandgap of 1.12 eV, and an electron affinity of 1.32 eV. Finally, the gate misalignment aspect of the proposed bio TFET-based pH sensor is emphasized by comparing sensitivity parameters. Hence, the proposed pH sensor can be used as a potential candidate for the futuristic application of biosensors.