An Analysis of the Linearity of a GaSb/Si Heterojunction TFET‐Based Highly Sensitive pH Sensor

This work presents a novel pH sensor design, referred to as the hetero‐VTFET‐pH sensor. It integrates GaSb/Si heterojunction vertical tunnel field‐effect transistors (TFETs) with split‐gate and step‐channel heterojunction TFET architecture. GaSb in the source region optimizes sensor sensitivity by enhancing carrier tunneling through GaSb–Si heterojunctions. The pH model is developed to evaluate the change in the potential drop due to pH change in the electrolyte. The pH model calculates the density of states corresponding to pH values for the electrolyte solution. Furthermore, the sensitivity analysis for drain current, transconductance has been done with a variation of the pH value of the electrolyte. The proposed pH sensor is simulated using SILVACO TCAD. In addition, linearity figures of merit are analyzed, including VIP2, VIP3, IIP3, and IMD3. The proposed pH sensor exhibits a voltage of ≈100 mV pH⁻¹, exceeding the Nernst limit of 59 mV pH⁻¹.