Exploring the bio-sensing application of high-k gate stack double gate trench channel TFET with lightly doped drain

Abstract

In this work, double gate trench channel (DG-TC) TFET based biosensor is presented for label free detection of biomolecules. Cavities are etched in the gate oxide across the source side for both the gates for biomolecules immobilization. To improve the performance of the device, stacked gate oxide with lightly doped drain (LDD) are introduced in DG-TC TFET. An extensive simulation study using ATLAS device simulator depicts enhanced ON current of 10− 5A/µm, lower average subthreshold slope (SS) of 34 mV/decade and high ON/OFF current ratio of 1014 with proposed DG-TC TFET owing to the integrated effect of trench channel configuration and enhanced tunneling area. To assess the sensing capability of the device, both neutral and charged biomolecules are considered and the effect of variation of the dielectric constant (k) and charge density (Nf) on device electrostatics are investigated and the sensitivity is estimated subsequently. The device with stack oxide structure records a high current sensitivity of 1.8×107 and 2.3×107 for positively and negatively charged biomolecules respectively with k = 12 in a completely filled cavity. Current sensitivity of the present device is also benchmarked against some of the existing TFET based biosensors to establish its superiority for future circuit and system level implementation.