The fabrication complexity and cost effectiveness in nanoscale regime have been one of the major issues in the modern biosensor. Therefore, to overcome such issue, this study investigates a junctionless dielectrically modulated electrically doped tunnel field effect transistor (FET) as a biosensor for application of label free detection. In this work, the authors have been considered the heavily doped silicon layer and two isolate gates for the formation of intrinsic and source regions underneath the control gate (CG) and polarity gate (PG) with appropriate work functions and polarity bias over silicon body which are similar to that of conventional tunnel FET. The proposed device structure is immune against doping control issues, avoids thermal budget, and fabrication issues. Moreover, the formation of nanogap cavity embedded within the CG dielectric is performed by etching of CG dielectric region towards the PG side for the purpose of sensing the biomolecules. The sensing ability of the proposed device has been evaluated in terms of varying the dielectric constant and charge density of the biomolecules. However, transfer characteristics are also evaluated with the variation in thickness and length of the cavity. All the simulations have been performed using ATLAS technology computer aided design device simulator.