<p>This paper presents and simulates a dielectric-modulated double gate heterojunction (SiGe/Si) vertical tunnel field-effect transistor (DMDGH-VTFET) based extremely sensitive label-free biosensor with source pocket intended for biological applications. In order to enhance carrier tunneling in source-channel (SiGe-Si) heterojunction this novel device uses a material with a tiny bandgap specifically SiGe in the source region. For the first time T-shaped drain architecture is used and which promise better performance and scalability because it boosts carrier injection, lowers DIBL, improves electric field distribution and minimizes contact resistance. Furthermore, the performance of label-free biosensors based on DMDGH-VTFET in both half-gate overlap and half-gate underlap configurations has been examined in this work. DMDGH-VTFET biosensor performance is examined in relation to energy band diagram, potential profile, electric field and drain characteristics for a variety of biomolecules including APTES (K = 3.57), Bacteriophage-T7 (K = 6.4), Apomyoglobin (K = 8.1) and Gelatin (K = 12). Additionally, the current study evaluated the figure of merits (FOMs) which primarily includes linearity and sensitivity by taking into account various dielectric constant values between 1 and 12. The biomolecules that are neutrally, positively and negatively charged have maximal values of the I_on/I_off sensitivity that reach as high as 2.96 × 10⁹&#xa0;mA/µm, 5.37 × 10⁹ mA/µm and 4.16 × 10⁹&#xa0;mA/µm respectively. It has been noted that the proposed device sensing performance can be greatly enhanced by optimizing the cavity height and length. The proposed biosensor sensitivity has been significantly improved for Neutral, Negative and Positive charged biomolecules as 6.14 × 10⁵, 5.27 × 10⁵ and 7.36 × 10⁵ respectively. It has shown better sensitivity when compared with other advanced biosensors.</p> Graphical Abstract <p></p>