Fabrication of integrated field-effect transistors and detecting system based on CVD grown graphene

Based on large-area multilayer graphene produced by chemical vapor deposition, an integrated field-effect transistor was fabricated in this work. A planar Au electrode was used as gate electrode integrated with graphene field-effect transistors (FETs) to generate perpendicular electrical fields between the gate and the graphene substrate. Graphene film was then transferred to cover indium tin oxide films which were used as drain and source electrodes. Via this process, the contact resistance between graphene and electrodes which were caused by polymethylmethacrylate (PMMA) residues in chemical vapor deposition process was almost eliminated. An electrical detecting system was designed to detect equivalent resistance of the FETs, which indicated that the performance of the FETs was associated with the width of conducting channel, the electrical field intensity between gate and graphene, and the ion concentration of electrolyte. Adenosine triphosphate (ATP) was selected as model electrolyte to verify the detecting system in this study. It was demonstrated that the integrated FETs could achieve high sensitivity to detect ATP as low as 10 pM and the equivalent resistance of the FETs showed a good correlation with ATP concentration from 10 pM to 10 μM. These results may provide a better direction and a common detecting platform for the design of integrated graphene FETs biosensors.