Si–Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications

Abstract

In this work, dielectric modulation strategy of gate oxide material that enhances the sensing performance of biosensors in junction less vertical tunnel field effect transistor is reported. The junction-less technique, in which metals with specific work functions are deposited on the source region to modulate the channel conductivity, is used to provide the necessary doping for the device's proper functioning. TCAD simulation studies of the proposed structure and junction structure have been compared, and it showed an enhanced rectification of 104 times. The proposed structure is designed to have a nanocavity of length 10 nm on the left- and right-hand side of the fixed gate dielectric which improves the biosensor capture area, hence the sensitivity. By considering the neutral and charged biomolecules with different dielectric, TCAD simulation studies were compared for their sensitivities. IOFF can be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain current. Additionally, it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold voltage. To explore the device performance when the nanogaps are fully filled, half filled, and unevenly filled, extensive TCAD simulations have been run. The proposed TFET structure is further benchmarked to other structures because it has better sensing capabilities.