In this paper, a dielectrically modulated symmetrical double gate, having dual gate material, Tunnel Field-Effect transistor with Buried strained Si1-xGex source structure, has been investigated as a biosensor. This structure is proposed for the very first time to electrically detect the biological molecules at very low power consumption. In the proposed biosensor structure, the top thin Si channel of TFET is overlapped with the Si1-xGexsource. This increases the tunneling area, due to which ON current of the biosensor also increases. To detect the biomolecules a nanogap cavity has been created over 1nm gate oxide. Also to decrease the short channel effects, dual-gate material with different metal work functions is used on both the symmetrical double gates. By varying the small bandgap material (Ge) mole fraction in the SiGe and after inserting different biological molecules (of the different dielectric) in a cavity, the variation in transfer characteristic, Ion/Ioff current ratio, SS along with their sensitivity is studied. Also, to signify the presence of biomolecules in the cavity, the gm/Id ratio as a sensing metric is studied under the sub-threshold region. Along with the fully filled biomolecules cavity, the partially filled cavity and the effect of a steric hindrance have also investigated in this paper with various non-uniform step patterns of biomolecules in the cavity.Because, in a more practical situation, the steric hindrance effect doesn’t allow the cavity to be entirely filled. Also, this paper addresses the optimization of drain current sensitivity, by different cavity length with different source overlapping cavity.

In this article, two nanotube structures have been proposed: namely, core-shell dopingless nanotube tunnel field effect transistor (CS-DL-NT-TFET) and Si0.5Ge0.5 source CS-DL-NT-TFET. The application of charge-plasma (CP) technique in their designing offers a fabrication advantage, which is the elimination of doping. Performance analysis of the two nanotube structures has been carried out on the basis of RF and analog parameters such as their transconductance (gm), transfer characteristics (ID-VGS), output conductance (gds), output characteristics (ID-VDS), cut-off frequency (fT), and gate capacitance (Cgg). Furthermore, the two devices have also been investigated for linearity and reliability based on parameters such as higher-order transconductances (gm3 and gm2), distortions [second-order harmonic distortion (HD2)], interception points [third-order input interception point (IIP3), second-order voltage interception point (VIP2), and third-order voltage interception point (VIP3)], and intermodulation distortion [third-order intermodulation distortion (IMD3)]. Based on the analysis of different parameters, the Si0.5Ge0.5 source CS-DL-NT-TFET was observed to have achieved an improved performance as compared to its Si-source counterpart due to a lower energy bandgap, higher mobility, and lower tunneling mass. The proposed device is optimized to maintain the uniformity of the induced CP within the source/drain regions. The optimized architecture enhances the device performance by attaining an average subthreshold slope of 31.38 mV/dec with a higher ON-current.

A new FoM to investigate a carefully engineered Schottky barrier (SB) TFET by accounting for dc power consumption, and silicon area, which are the key consideration for energy efficiency and cost of the biosensors, is reported in this paper. The SB TFET utilizes source overlap, drain underlap, and nano-cavity near the source region to detect biomolecules by accounting non-ideality, i.e., steric hindrance (SH). The sensitivity due to drain current ID, ON-OFF ratio ION IOFF, average subthreshold swing AVSS, threshold voltage VTH transconductance gm are thoroughly investigated. The proposed FoM is utilized, and impact analysis is carried out by considering neutral biomolecules mainly due to changes in their dielectric constants, SH step profiles, and variation in the pocket length. After the detailed analysis by considering the case of APTES biomolecules in different step profiles, the concave profile realized an optimized FoM of 30nW1nm1. However, when k is varied, the FoM was realized nearly 26nW1nm1 for all the k>5. The improvement in FoM is observed around 67% when pocket length of 5 nm is used as compared to when it is not used. Comparisons with the published papers having similar dimensions TFETs biosensors by mainly targeting ION sensitivity and corresponding FoM are presented, and the proposed nano SB TFET was found to achieve significantly higher results.