In this fast-growing technological world biosensors become more substantial in human life and the extensive use of biosensors creates enormous research interest among researchers to define different approaches to detect biomolecules. The FET based biosensors have gained a lot of attention among all because of its high detection ability, low power, low cost, label-free detection of biomolecules, and CMOS compatible on-chip integration. The sensitivity of the biosensor inversely proportional to device size since they detect low concentration yields quick response time. Although FET based biosensor is having a lot of advantages among others but the short channel effects (SCE's) and the theoretical limitation on the subthreshold swing (SS > 60mv/dec) of the FET leads to restrict device sensitivity and also have higher power dissipation due to the thermionic emission of electrons. To avoid these problems researchers focus shifts to the new technology FET based biosensors i.e. TFET based biosensors which are having low power and superior characteristics due to Band to band tunneling of carrier and steep subthreshold swing. This manuscript describes the full-fledged detail about the TFET based biosensors right from unfolding the device evaluation to biosensor application which includes qualitative and quantitative parameters analysis study like sensitivity parameters and different factors affecting the sensitivity by comparing different structures and the mechanisms involved. The manuscript also describes a brief review of different sensitivity parameters and improvement techniques. This manuscript will give researchers a brief idea for developing for the future generation TFET biosensors with better performance and ease of fabrication.
In this paper, a Z‐shaped gate dielectric modulated (DM) tunnel field‐effect transistor‐(TFET) based biosensor with extended horizontal n+ pocket in the source region is proposed and different performances were investigated. Effective structural modification has been done by considering the filed induced quantum confinements effects to enhance the various performances of the device in terms of ON current (Ion) and threshold voltage. The horizontal pocket beneath the source region of the ZHP‐DM‐TFET biosensor enables the vertical tunneling besides the lateral tunneling which leads to enhancement of device performance in terms of short channel effects, low OFF the current. A comparative study is also carried with existing biosensors and it is observed that the ZHP‐DM‐TFET biosensor shows superiority over the other biosensors due to its irregular arrangement of the gate and the horizontal n+ pocket provides. The sensitivity analysis of the device was further investigated by varying the dielectric constant of the biomolecules inside the nanocavity for the value from K = 1 to K = 10. The ZHP‐DM‐TFET biosensor shows a significant improvement in threshold voltage sensitivity 20% (k = 2), 35%(K = 4) and a 102 improvement in Ion/Ioff ratio. The impact of the thickness of the n+ pocket (pocket) over the sensitivity of the biosensor is also investigated.
In this article, a dielectric modulated triple metal gate-oxide-stack Z-shaped gate horizontal source pocket Tunnel Field-Effect Transistor [DM-TMGOS-ZHP-TFET] structure has been investigated for the application of label free-biosensor. This work explores the advantage of gate work function engineering along with the gate-oxide-stack approach for the Z-shaped gate horizontal source pocket Tunnel Field-Effect Transistor [ZHP-TFET] for the first time. An asymmetric nano-cavity is created adjacent to the source-channel junction to immobilize the target biomolecules conjugation to the proposed device. The sensitivity of the device is thoroughly investigated in terms of average subthreshold swing (ss), threshold voltage(Vth) and the switching ratio (Ion/Ioff) of the proposed device with the variation of the dielectric constant value inside the nano-gap under the gate electrode. The device characteristics are investigated with different combinations of metal work functions to match the desired feature and sensitivity of the device. In addition, the sensitivity analysis of the proposed device is analyzed in the presence of both positive and negative charged biomolecules in the cavity region to study the charge effect on label-free detection of the device. A comparative study is conducted between a single metal gate ZHP-DM-TFET [SMG- ZHP-DM-TFET] biosensor with the DM-TMGOS- ZHP-TFET biosensor explores the advantage of gate-work function engineering with a gate-oxide-stack approach. Interestingly the DM-TMGOS- ZHP-TFET biosensor shows superior results with a high current ratio sensitivity of 103 which is ten times more than the SMG- ZHP-DM-TFET biosensor and this deice also exhibits low subthreshold characteristics.
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