Design and Performance of a Dielectrically Modulated Electron–Hole Bilayer Tunneling FET Biosensor: Effects of Nanogap Cavity on Sensitivity and Voltage Requirements

This study investigates a biosensor utilizing a dielectrically modulated electron-hole bilayer tunneling field-effect transistor (DMEHBTFET) for high-sensitivity applications through numerical device simulation. The research examines three configurations to assess the influence of nanogap cavity placement on biosensor performance concerning bias supply voltage: standard DM-EHBTFET, overlapped DM-EHBTFET, and non-Overlapped DM-EHBTFET. In the standard configuration, the nanogap cavities span both gates. The overlapped design positions them within the overlapping regions of both gates, whereas the non-overlapped configuration locates the cavities in the non-overlapping areas of both gates. Simulation results reveal that the standard and overlapped biosensors require minimum bias voltages of V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub>=5.5V and V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub>=4.5V, respectively, for detection, while the non-overlapped biosensor necessitates only 1V. The nanogap cavity design in the non-overlapped DMEHBTFET isolates specific regions of both gates, with a length of LOV, from the channel by a 2-nanometer HfO2 insulator, thereby enhancing electrostatic coupling. This non-overlapped device consumes 82% less bias voltage than the standard version, rendering it suitable for low-voltage applications. The drain current sensitivity of the non-overlapped biosensor for a biomolecule with K=12 was 431 and 1208 times greater than that of the overlapped and standard biosensors, respectively. For K=12, the non-overlapped biosensor exhibits a drain current sensitivity of 3e9, an on/off current ratio sensitivity of 2.3e9, a cutoff frequency sensitivity of 2.8e8, and a transconductance sensitivity of 5.45e8. The performance of the non-overlapped biosensor is evaluated in terms of steric hindrance, and it surpasses recent DM-TFET biosensors, establishing it as a promising candidate for high-sensitivity applications.