Ultra Sensitive Label-Free Detection of Biomolecules Using Vertically Extended Drain Double Gate Si₀.₅Ge₀.₅ Source Tunnel FET.

This work reports a vertically extended drain double gate Si0.5Ge0.5 source tunnel FET for the biomolecules detection using its electrical properties modulation in presence of biomolecules like cell, DNA, protein, etc. The reported biosensor has a dual source of Si0.5Ge0.5 and two cavities above each source-channel interface for the immobilization of biomolecules. This immobilization modulates the screening/tunneling length and energy range available for tunneling due to the dielectric constant and charge density variations of the biomolecules. The dual cavity structure increases the control of biomolecules on the source to channel tunneling probability and thus realizes an increased control on electrical performance parameters of the biosensor enabling it to have a higher sensitivity towards the biomolecules. Further, the cavity length of the reported biosensor is kept as 45 nm making it suitable for large sized biomolecules and polymers detection also. Our study demonstrates that the reported biosensor structure is resilient towards the process variations and temperature effects. Moreover, the effect of dielectric modulation and charge density modulation has also been analyzed in terms of the variation in the drive current, ON state current, threshold voltage, transconductance, and sub-threshold slope (SS). The sensitivity of the reported biosensor is also compared with the existing biosensors and it is found to be highly sensitive.