Dielectric Modulated Nanotube Tunnel Field-Effect Transistor as a Label Free Biosensor: Proposal and Investigation

Dielectric modulated (DM) field-effect transistors (FET) have gained significant popularity for label-free detection of biomolecules. However, the inherent short channel effects limit their sensitivity, scalability and energy-efficiency. Therefore, to realize the true potential of the DMFET based biosensors, in this work, we propose a highly scalable, extremely sensitive and energy-efficient DM nanotube tunnel FET (NT-TFET) biosensor for label-free detection of biomolecules by modifying the structure of the conventional NT-TFET. The modified architecture facilitates the realization of a nanocavity at the source-channel tunneling junction and also provides stability to the immobilized biomolecules. We have performed an extensive analysis of the performance of the proposed DM NT-TFET biosensor in the presence of different representative target biomolecules characterized by different dielectric constants, and/or ionized charge densities using calibrated TCAD simulations. Our results indicate that the proposed DM NT-TFET exhibits an extremely high threshold voltage sensitivity (<inline-formula> <tex-math notation="LaTeX">${S}_{{V}_{{{th}}}}$ </tex-math></inline-formula>) of 0.44, a high selectivity exceeding four orders of magnitude, ON-state current sensitivity (<inline-formula> <tex-math notation="LaTeX">$\textrm {S}_{\textrm {I}_{{{ON}}}}$ </tex-math></inline-formula>) of more than five orders of magnitude and could be a promising alternative to the conventional FET based dielectric modulated biosensors. Moreover, the sensitivity of the proposed DM NT-TFET could be further improved by utilizing alternate source materials with lower bandgap or by probing the transient response of the drain current and exploiting the difference in the settling time for different biomolecules with different dielectric constant (<inline-formula> <tex-math notation="LaTeX">$\kappa$ </tex-math></inline-formula>).