Design and Simulation of a High-Performance Tunneling Field Effect Transistor-Based Biosensor Using a Heterojunction Electron-Hole Bilayer

This study introduces a novel dielectrically-modulated heterojunction electron-hole bilayer tunnel field-effect transistor (DM-HEHBTFET) for bio-sensing applications. The device features a Ga 0.85 Sb 0.15 As/Ga 0.8 In 0.2 As heterojunction and a p-type pocket in the channel, achieving a remarkably low threshold voltage (V T ) of 20 mV, an average subthreshold slope (SS) of 5.7 mV/dec, and a leakage current (I OFF ) as low as 5 × 10 −11 A/μm. The staggered bandgap in the heterostructures enhances electric field control, enabling lower gate voltage operation. Furthermore, the strategically positioned nanogap cavities in non-overlapping regions of the top and bottom gates effectively mitigate gate control issues over the channel, ensuring improved device performance. A modified design, the modified DM-HEHBTFET, is also proposed, featuring source and drain regions engineered with Ga 0.85 Sb 0.15 As/Ga 0.8 In 0.2 As heterojunctions. This design mitigates leakage current and improves the average subthreshold slope (SS). For biomolecules with a dielectric constant of 12, the modified biosensor exhibits a drain current sensitivity (S current ) of 2.6e4, average SS = 2.7 mV/dec, and I OFF = 1e-12 A/μm. The device’s performance is assessed by examining steric hindrance and band tailing effects. The modified biosensor outperforms recent DM-TFET biosensors, making it a promising candidate for low-power, high-switching speed bio-sensing.