Electron-hole bilayer TFET-based biosensor using hybrid tunneling mechanism for high off-state current and on-off current ratio sensitivities

To facilitate the injection of biomolecules and device integration, we design a novel vertical biosensor based on an electron-hole bilayer tunnel field-effect transistor. This biosensor utilizes the off-state point tunneling current for biomolecules detection, which makes its off-state current sensitivity (S_Ioff) independent of gate voltage, contributing to reduced power consumption. Its on-state current depends on the line tunneling between the electron-hole bilayer, allowing higher on-off current ratio sensitivity (S_Ion/Ioff) under low bias conditions. Investigations reveal enhanced sensitivity toward negatively charged biomolecules with high dielectric and charge density. Furthermore, optimal S_Ioff and S_Ion/Ioff are achieved when the bio-cavity width equals 4 nm. Investigations demonstrate that superior sensing performance can be obtained when probes with a high filling rate are concentrated on the right side of the bio-cavity, and the biomolecule filling rate significantly affects the detection ability of high-k biomolecules. Numerical calculations demonstrate that the proposed biosensor exhibits exceptional S_Ioff (∼10¹³) and S_Ion/Ioff (∼10¹²) at 0.5 V, significantly advancing the application potential of TFET-based biosensors in low-power fields.