Detection sensitivity analysis of a vertical TFET biosensor using a negative capacitance GaSb/InGaAs electrolyte pH sensing system

This paper analyzes a vertically grown GaSb/InGaAs hetero-junction negative capacitance vertical tunnel FET (Hetero-NC-VeTFET) sensor with a pocket in the source region to improve device performance by generating a negative capacitance effect. The ferroelectric (FE) materials enhance gate performance at low gate voltages by amplifying the input signal. The study proposes a Bio-TFET with an overlapping hetero-structure for pH sensing, with the electrolyte (water) region modeled as an intrinsic semiconductor material with a bandgap of 1.12 eV and permittivity of 80. SILVACO ATLAS TCAD has been used to simulate the electrolyte-based TFET pH sensor, which examines the impact of pH changes on various device characteristics, including drain current, transconductance, surface potential, and their sensitivities. Using low band gap materials, GaSb and InGaAs, at the source/channel junction results in efficient tunneling, leading to enhanced sensitivity of the device. The negative capacitance with the GaSb/InGaAs configuration achieved vertical tunneling in the proposed device, thus improving the pH sensitivity. A detailed sensitivity analysis has been performed to examine the impact of negative capacitance on the drain current voltage and transconductance sensitivity (order of 10⁵).