Evaluation of Dielectrically Modulated and Fringing Field Tunneling Field Effect Transistor Biosensors Devices

Abstract

An evaluation of a dielectrically modulated (DM) and a fringing field (FF) biosensor based on a tunneling field-effect transistor (Bio-TFET) by 2D numerical simulation is presented. The bio detection is based on the presence of a biomaterial with a distinct dielectric constant (k) on the sensitivity area. The performance of the devices is compared in terms of drain current in the ambipolar region (i.e., for negative gate voltage in an n-type Bio-nTFET device) due to the variation of the k, drain underlap length (LUD), and the presence of charges (QBio) into the biomaterial/silicon interface. The results show that the DM biosensor with LUD = 25 nm exhibits a higher sensitivity in all k simulated compared with FF biosensor, resulting in more than 2 orders of magnitude for k = 10. In the presence of charges, the DM shows a higher sensitivity in all of the range studied. Higher sensitivity values over a wider range of LUD and QBio are desirable and DM Bio-TFET achieves a better result compared with the FF Bio-TFET. Results show a new outlook for each type of biosensor.