Comparative Analysis of Symmetrical/Asymmetrical Vertical Electrolyte‐Insulated Semiconductor Tunnel FET for pH Sensor Application

Abstract

This study investigates symmetrical/asymmetrical vertical electrolyte‐insulated semiconductor Tunnel field effect transistors (TFETs) (SV‐EIS‐TFET/ASV‐EIS‐TFET) for their application as pH biosensors. On the basis of device‐level simulations, the underlying physics of all architectures is explored and the comparative biosensing abilities of pH biosensors are evaluated. A vertical electrolyte Bio‐TFET with overlapping electrodes is presented in this study. The pH response is measured by observing the change in drain current and potential when the pH of the injected solution transitions from a lower to a higher level. As an intrinsic semiconductor material, electrons and holes in the electrolyte represent mobile ions in the solution. The region of the electrolyte has an electron affinity of 1.32 eV, a bandgap of 1.12 eV, and a dielectric constant of 78. Double gate structures raise concerns about correctly aligning the right and left gates because of their sensitivity impact. An analysis of the effect of gate misalignment on biosensor surface potentials, drain currents, and transconductance is presented. Furthermore, pH value ranges of 1–14 are considered for various sensitivity parameters. Simulations are performed using Silvaco TCAD for the SV‐EIS‐TFET and ASV‐EIS‐TFET biosensors.