A Device Simulation-Based Investigation on Dielectrically Modulated Fringing Field-Effect Transistor for Biosensing Applications

In this paper, a dielectrically modulated fringing field-effect-transistor (DMFFET) structure has been introduced as the transducer element for electrochemical biosensing applications, where the gate-induced fringing field has been exploited for transduction. This detection principle is different from that of the direct gate field modulation in conventional dielectrically modulated field-effect-transistor (DMFET)-based transducers. This paper explores the transduction mechanism from the electrostatics and carrier transport mechanism of DMFFET, in comparison with conventional double gated (DG) DMFET, based on extensive device-level simulation. The transducer response for the DMFFET/DG-DMFET structures has been estimated in terms of the drain current sensitivity, which is defined in the dB scale. In this paper, the effects of gate/drain biases have been investigated in details, and a strategy has been proposed for identifying suitable biasing ranges of operation based on half width at full maxima limit of sensitivity. The relative influences of electron trapping/de-trapping at the interfaces are also indicated on the transducer responses. Further, the role of different gate-related structural parameters of DMFFET has been considered for sensitivity-optimization. The comparative performance study with the reported DMFETs indicates the inherent superiority of DMFFET for transduction.