Comparative analysis of gate structure dependent FET-based biosensor

Abstract

In this work, four biosensors with different gate structures based on MOSFETs are examined. A conventional back gate and three different front gate-based structures are assessed in terms of change in the electrical parameters of transfer characteristics and sensitivity. Most importantly, all four structures are analyzed to consider the realistic process of biomolecule detection with varying fill-in factors of biomolecules, and sensitivity is calculated between the anti-iris antibody (bio target) and iris-antigen (bioreceptor). In a back-gate structure, the electrical parameter is only affected by the negative charge density of biomolecules which limits this topology to detect the neutral biomolecules, while in front-gate-based structures, the electrical parameters are affected by both dielectric permittivity and negative charge density; thus, front-gate-based biosensor structures show the applicability to detect the charged as well neutral biomolecules. The front gate single cavity and front gate mid cavity show the highest sensitivity for all the combinations of fill-in factors. This comparative study of different gate structures for varying fill-in factors on different locations of biomolecules in the cavity or sensing region proposes the guidelines for making suitable choices for MOSFET-based biosensor development.