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

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.