Impact on performance of dual stack hetero- gated dielectric modulated TFET biosensor due to Si1-xGex pocket variation

In this work, the performance evaluation of a dual stack hetero-gated pocket modulated tunnel FET (DSHGPM-TFET) based biosensor is presented. In the proposed device, cavity is formed by etching a portion of gate metal on both side of channel. The device contains a Si1-xGex pocket buried in the source region, where x (Ge mole fraction) is varied and effect on ION, VTH, and SS sensitivity is analyzed. The effect of x (=0, 0.4, 0.8, 1) and k (= 1, 5, 7, 10, 12) variation in DSHGPM-TFET is compared and noted. Also, the subthreshold swing (SS) and ION/IOFF ratio vs. dielectric constant at different x are plotted. Sensitivity is observed in the presence of neutral and charged (positive/negative) biomolecules within the cavity. Results show that increasing x of the pocket as well as k, enhances the sensitivity parameters. It is seen that sensitivity increases (decreases) with positive (negative) charged biomolecules. The work is further extended to study the performance of biosensor in non-ideal conditions. The effect of steric hindrance is studied by employing four different step profiles in cavity-concave, convex, decreasing, and increasing for two fill-factor (FF) 40% and 61%. The dynamic range of the proposed biosensor is estimated by varying x. Finally, the proposed sensor is compared with other biosensors existing in literature. © 2022 Elsevier Ltd