<p>In this paper, a drain-engineered Ge/In_0.53Ga_0.47As heterojunction-based doping less TFET (DE-HJ-DLTFET) is proposed for label-free biosensing applications. To reduce the fabrication cost and random-dopant-fluctuation (RDF) effects, a doping-less TFET is considered a biosensor. A Ge/In_0.53Ga_0.47As heterojunction is regarded at the source-channel interface to reduce the potential barrier, thus improving the DE-HJ-DLTFET drain current (I_DS) and SS value. Then, a small metal strip is inserted in the oxide region above the source-channel interface to improve the BTBT rate and I_DS for the proposed device at low gate voltages. Moreover, a drain metal with a combination of two different work function metals is considered to reduce leakage current (I_OFF) and ambipolar conduction in the DE-HJ-DLTFET. As a result, the proposed DE-HJ-DLTFET shows remarkable I_DS sensitivity and turn-on voltage sensitivity of ~ 10⁸, 0.85 in comparison to other advanced biosensors. Performance is evaluated under the influence of varying biomolecular charges. Furthermore, the improvement in ON-current and reduced I_OFF improved the I_ON/I_OFF sensitivity of the DE-HJ-DLTFET biosensor under the presence of different biomolecular charges. Therefore, these improvements in I_DS, turn-on, and I_ON/I_OFF sensitivity make the DE-HJ-DLTFET a good candidate for next-generation low-power sensing applications.</p>