Dual Cavity Dielectric Modulated Ferroelectric Charge Plasma Tunnel FET as Biosensor: For Enhanced Sensitivity

This work reports a biosensor based on the dual cavity dielectric modulated ferroelectric charge plasma Tunnel FET (FE-CP-TFET) with enhanced sensitivity. By incorporating underlap and dielectric modulation phenomena, ultra sensitive, and label-free detection of biomolecules is achieved. The cavity is carved underneath the source-gate dielectric for the immobilization of the biomolecules. The ferroelectric (FE) material is used as a gate stack to realize a negative capacitance effect to amplify the low gate voltage. To avoid the issues with metallurgical doping such as random dopant fluctuations (RDFs), ambipolar conduction, and increased thermal budget, the charge plasma concept is deployed. Based on our exhaustive ATLAS 2D TCAD study, the electric field, hole concentration, and energy band diagram of the proposed device are critically analyzed to provide a better insight into the biosensor working mechanism. Here, two different figures-of merits (FOMs) for the proposed biosensor are investigated such as sensitivity and linearity. Sensitivity has been measured in terms of drain current, ${I}_{ \mathrm{\scriptscriptstyle ON}}$ to ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio, electric field, and transconductance sensitivity. Linearity analysis of the proposed structure includes ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio. The reported biosensor is capable of detecting several biomolecules such as (neutral and charged as well) Streptavidin (2.1), 3-aminopropyltriethoxysilane (APTES) (K $=3.57$ ), Keratin (K $=8$ ), T7 (K $=6.3$ ) and Gelatin (K $=12$ ). It was observed that the optimized cavity structure demonstrates high drain current sensitivity ( $2.7\times {10}^{{8}}$ ) as well as high ${I}_{ \mathrm{\scriptscriptstyle ON}}/\text {I}_{ \mathrm{\scriptscriptstyle OFF}}$ sensitivity ( $1.45\times {10}^{{8}}$ ). Further, the linearity analysis shows that the Pearson’s coefficient of both structures have been achieved as ( ${r}^{{2}} \ge0.8$ ). It is conferred from the results that our biosensor can be a better alternative for the detection of the various neutral and charged biomolecules.