Gate-on-Drain Overlapped L-Shaped Channel Tunnel FET as Label-Free Biosensor

Suman Das,Bikash Sharma

doi:10.1007/s12633-021-01285-z

Abstract

In this work gate-on-drain L-shaped channel Tunnel FET is proposed to detect various biomolecules through label-free bio-sensing detection technique. Biomolecules can be detected in the proposed structure through modulation of ambipolar current between channel and drain. Modulation of ambipolar current is performed by extending gate over drain in order to create a gate to drain overlap (cavity) by etching the specific portion of the gate. Trapped biomolecules within cavity gets immobilized. Immobilized biomolecules change the drain to channel tunneling width, thus changing the ambiploar leakage current. Drain doping and cavity length was fine-tuned to achieve better sensitivity in terms of ambipolar current and ambipolar knee voltage shift with and without presence of biomolecules. A maximum sensitivity of 3.8 × 107 is achieved for drain doping of 5 × 1019 donors/cm3 and cavity length of 60 nm. A high value of sensitivity is achieved for each biomolecules when drain doping ranged from 1019 donors/cm3 to 5 × 1019 donors/cm3 and cavity length ranged between 40 nm to 50 nm. Effect of differently charged biomolecules on sensitivity has also be structured.

Highlights

Detection of biomolecules using biosensor has become a fastgrowing field of study in present COVID 19 pandemic situation
Gate on drain overlapped tunnel Field effect transistor (FET) as bio sensing application was first reported by abdi. et al [24]
Highest sensitivity is achieved for K = 10 and drain doping = 3 × 1019 donors/cm3

Summary

Introduction

Detection of biomolecules using biosensor has become a fastgrowing field of study in present COVID 19 pandemic situation. Overlap between gate and drain, widens the tunneling barrier width at the channel-drain interface at negative gate voltages, which modulate the ambipolar current In this manuscript for the first time a gate-on-drain overlapped L-shaped channel TFET (GDOL-TFET) has been reported to sense different biomolecules having dielectric constant between K = 1 to 10 which. At a particular gate bias, VGS=Vknee(ambipolar) the valance band of channel start to overlap conduction band of drain as a result electron start to tunnel through the tunneling window and a tunneling current can be obtained which is undesirable for digital circuit application where leakage current should be minimum. The drain current and its corresponding energy band diagram is shown in Fig. 2(c) and (d) which state the operation

Air I dielectric

Results and Discussions

Optimization of Lcavity

Effect of Positive and Negative Charged Biomolecules in Cavity

Conclusion

Data Availability Yes