Simulation of BioGFET sensors using TCAD

Abstract

We used a commercial TCAD simulator for the study of liquid-gate Graphene FETs as antibody-based sensors. To model the graphene layer, a zero-bandgap semiconductor with a linear density of states relationship in both the conduction and valence bands near the edge of the bands was adopted. The electrolyte which forms the liquid gate was also modeled as a semiconductor with tuned parameters to reproduce the behavior of a dilute PhosphateBuffer Saline (PBS) solution with pH = 7.4. Antibodies are anchored to the graphene surface and their effect is simulated with a charged cube box with a size similar to the one of the IgG antibody and a charge concentration similar to the charge usually carried by an anibody. The binding of the antibody with the antigen protein (Ab-Pr) complex is also represented in the simulator with a charged box carrying a different charge. We have calculated the ID-VFG curves for different numbers of antibodies anchored to the surface of the graphene and analyzed the behavior of the sensor as a function of the number of antibody-protein complexes.