Polarity Control SiGe-Source Tunnel Field Effect Transistor-based Biosensor for Bio-sensing Applications

In this paper, a polarity control, SiGe-source, Tunnel Field-Effect transistor (PC-SiGe-TFET)-based biosensor has been proposed for label-free detection of biomolecules. The $\mathbf{n}^{+}$drain and $\text{P}^{+}$source regions are created in the intrinsic silicon-SiGe body of the proposed device by using the polarity-controlled concept. In addition, a nano-cavity is created in the gate oxide towards the tunneling junction to modulate the tunneling mechanism via the immobilized biomolecules. The sensing performance of the proposed PC-SiGe-TFET biosensor is analyzed employing four different types of biomolecules, namely Biotin $(k=2.1)$, 3-aminopropylteriethoxysilane $(k=3.57)$, Femo-cytochromr-c $(k = 4.7)$ and Bacteriophage T7 $(k=6.3)$. The PC-SiGe-TFETbased biosensor exhibits higher sensitivity in terms of drain current $(\mathbf{I}_{DS})$, threshold voltage $(\mathbf{V}_{Th})$, and subthreshold swing (SS) and ON-OFF current ratio $(\mathbf{I}_{ON}/\mathbf{I}_{OFF})$. The sensitivity of the proposed biosensor has been evaluated with both neutral and charged biomolecules. The sensitivity of the PC-SiGe-TFET biosensor has also been investigated in terms of nano-cavity dimensions (length and width), as well as the various non-uniform step profiles (steric hindrances) of biomolecules in the nano-cavity.