The physical modelling of the tunnel field effect transistor (TFET) is done in this study. The Silvaco TCAD tool is used to design and simulate the TFET structure. The FET device has attracted a lot of attention as the ideal tool in creating biosensors because of its appealing properties such as ultra-sensitivity, selectivity, low cost, and real-time detection capabilities in sensing point of view. These devices have a lot of potential as a platform for detecting biomolecules. Short channel effects, specificity, and nano-cavity filling have all been improved in FET-based biosensors. FET-based biosensors are appropriate for label-free applications. Random dopant variations and a thermal budget are seen during the construction of a JLFET. To overcome this problem, the charge-plasma-based concept was established in FETs in this study. Different metallurgical functions for electrodes were employed in this biosensor to behave as a p-type source and n-type drain. To alleviate the short channel effects, a dual material gate work function for the gate electrode was devised, as well as a double gate architecture. Biomolecules can be neutral or charge-based, and both types of biomolecules can be identified using a proof-of-concept FET-based biosensor. Changes in the drain current (Id) of the device were achieved by varying dielectric values and charges in the cavity region with variable cavity lengths.