This paper reported a comparative study of the full gate and short gate Schottky Barrier (SB) Tunnel FET (TFET). In this work, we have employed a short gate architecture for the SB TFET. The proposed device has a short gate over the source side with gate-drain underlap. In addition, dopant segregated source/drain (S/D) is formed to effectively modify the height and width of the Schottky barrier. The proposed device effectively reduces the gate control over the drain side. As a result, the device’s leakage current due to ambipolar conduction on the drain side decreases. Consequently, the proposed device offers significant advantages over the full gate SB TFET. Dielectric modulation and Schottky barrier tunneling were used in this proposed work to identify the biomolecules. For this purpose, a nanogap cavity is created under the gate and semiconducting channel near the source end. The proposed device is named Short Gate Dielectric Modulated Dopant Segregated SB TFET (SG DM DS SB TFET). The device’s performance has been evaluated in terms of energy band variation, surface potential, electron tunneling rate, electric field, and transfer characteristics. In addition, the device sensitivity parameters in terms of I_ON sensitivity, I_ON/I_OFF sensitivity, and V_TH sensitivity. The proposed device has the advantages of being devoid of random dopant fluctuations, having a low thermal budget, device variability, and being easier to fabricate. The device’s legitimacy as a label-free biosensor is confirmed by the results.