20:T53c,This paper compares circular gate (CG) tunnel field effect transistor (TFET) and uniform gate Heterojunction (HJ) TFET as label-free biosensors based on dielectric modulation. Neutral and charged biomolecules with different values of dielectric constant are considered. Sensitivities of partially filled nanogaps arising out of steric hindrance in both the biosensors for concave, convex, increasing and decreasing step profiles of biomolecules are compared. The effect of probe position on sensitivities of the two biosensors is reported for various cases. A status map is presented, plotting the sensitivities of some of the most significant works in applications of FET as label-free biosensors along with sensitivities of the proposed devices. CG TFET exhibits higher sensitivity than HJ TFET due to its non-uniform gate architecture. The sensitivities of the TFETs are highly dependent on the position of biomolecules (steric hindrance and probe position) with respect to the tunnel junction. A maximum sensitivity of 1.31 × 10 ⁸ (3.382 × 10 ⁶ ) is achieved for fully filled nanogap in CG TFET (HJ TFET) for dielectric constant 12.21:T4d1,A comprehensive evaluation of sensitivity between double gate tunnel FET and n+ pocket doped vertical tunnel FET based label-free biosensors is reported in this work. Both the biosensors possess nanogaps on the left and right of the fixed dielectric (HfO2) which enhances the capture area of the biosensors. Comparison has been made on the TCAD simulation studies of their sensitivities considering neutral/charged biomolecules having different dielectric constants. The sensitivity of VB is found to be approximately 10 ⁴ times the sensitivity of DB due to its current conduction in both vertical and lateral directions. Also, the effects of steric hindrance and irregular position of probes/receptors are analyzed to understand the non-ideal behavior of the sensors. Sensitivity is calculated from the simulated results for four different cases of partially filled nanogaps - decreasing, increasing, concave and convex profiles. It rises by about 5-7% when filled factor is increased from 40 to 66%. Finally, benchmarking of proposed VB is done against other published literature as it gives better result in terms of sensitivity.22:T4b5,In this paper, we have proposed a charge plasma-based doping less double gated tunnel FET (DLDGTFET)-based biosensor using dielectric modulation with a cavity introduced at the source side for the label free sensing of the biomolecules. These biomolecules are immobilized in the cavity region to induce drain current. The sensing of the biomolecules is based on the drain current of the device while the drain current is based on the dielectric constant and the interfacing charges of the biomolecules. The cavity length is varied between 25 and 30 nm and different dielectric constants have been used. The expansion of the cavity length results in slight reduction of the drain current due to lowering of the capacitance. Higher dielectric constants result in better drain current values which leads to an increase in the sensitivity of the device. The maximum sensitivity attained was as high as

$1.0\times 10^{10}$

. As compared to other transistors, DLDGTFET provides better sensitivity as a biosensor and also the leakage current is low.

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