A high-sensitivity vertical electron–hole bilayer TFET biosensor based on charge plasma for label-free detection

To address the low detection sensitivity and high-power consumption of conventional TFET biosensors, this paper proposes and numerically investigates a novel TFET-based biosensor. It induces an electron–hole bilayer via the charge-plasma principle and uses line tunneling as the on-state mechanism. An InAlAs barrier layer suppresses off-state leakage, and the overlap between the bio-cavity and the barrier layer is optimized to enhance device performance. For neutral biomolecule detection, threshold-voltage sensitivity, on-state current sensitivity, and on–off current ratio sensitivity increase with dielectric constant, reaching maximum values of 1276 mV, 1.3×10 10 , and 1.9×10 9 , respectively. Negatively charged biomolecule detection shows strong charge–dielectric synergy, with severe degradation under low- k and high- σ bio conditions. Optimization indicates that, under certain deviations in size and work function, the device can still detect biomolecules effectively. Temperature strongly affects current-based sensitivities, necessitating compensation, while non-uniform filling favors biomolecule enrichment at the cavity bottom. Moreover, nonlinear distortion analysis demonstrates strong resistance to nonlinear distortion at V gs = 1 V, particularly for high- k biomolecules. This work provides a theoretical basis for high-performance TFET biosensors in point‑of‑care diagnostics.