A label-free dielectric-modulated biosensor using split-source double gate TFET

Abstract

This work presents split source double gate (SSDG) dielectric modulated (DM) Tunnel Field Effect Transistor (TFET) for label free biosensing. The nanogap cavity is considered near the source region to lodge an enormous amount of biological molecules and HfO₂ is considered towards the drain side. In SSDG-DMTFET the source is split in two separate sections. The lower half is formed out of Germanium, whereas the upper part is comprised of Silicon. Reduced current leakage, improved inclination with respect to SS, and decreased ambipolar conductance are the results of these hetero-structural modifications. It also provides a comparatively improvement in current sensitivity $S_n$ and SS due to its enhanced tunneling junction area. The $S_n$ is evaluated for fully filled nanogap cavity under the neutral biomolecules with wide variation in dielectric constant (k). We have reported the Subthreshold Swing (SS), input characteristics, output characteristics, energy band diagram, threshold voltage $\left(V_{TH}\right)$ and $I_{ON}/I_{OFF}$ ratio by varying k from 1 to 12 for uncharged biomolecules within the nanogap. The performance is also evaluated for partially and non-uniformly filled nanogap with wide variation in dielectric constant (k). Furthermore, sensitivity of SSDG-DMTFET is compared with the sensitivity of existing FET/TFET based biosensors.