Abstract <p>This work presents the design and analysis of a high-sensitivity Nanosheet Schottky Tunnel Field-Effect Transistors (NS-STFETs) for biosensing applications. The proposed device leverages Schottky source/drain contacts and stacked nanosheet geometry to enhance electrostatic control and tunneling efficiency. Device performance was investigated using Sentaurus TCAD simulations. The biosensor demonstrates promising characteristics, including an <i>I</i>_ON of 2.43 × 10^–5 A, <i>I</i>_OFF of 1.33 × 10^–18 A, and <i>I</i>_ON/<i>I</i>_OFF of 10¹³ for protein biomolecules with a dielectric constant of <i>k</i> = 8. Further analysis was carried out to evaluate the influence of biomolecules with varying dielectric constants (<i>k</i> = 1 to 20), different fill factors (25–100%), and positively/negatively charged biomolecules with charge densities from –10¹¹ to +10¹¹. The results confirm that higher fill factors and charged biomolecules have a significant impact on sensitivity, while the device maintains stable operation under various conditions. Overall, the NS-STFET biosensor exhibits high sensitivity, low power consumption, and scalability, making it a strong candidate for next-generation label-free diagnostic platforms.</p>