| 초록 |
The sensing characteristics of graphene devices have varied from case to case, and the sensing mechanism has not been satisfactorily determined. In an effort to address this issue, we have developed a silica-assisted chemical vapor deposition (CVD) to directly synthesize graphene mesh structures. This approach allow the engineering of graphene defects and enables further investigation of their effect upon graphene-based sensor characteristics. Compared with Graphene field-effect transistors (FETs), Graphene mesh FETs having large increments of Dirac point shift such even sometimes exceeded the Nernst limit. This increments were attributed to the defect-mediated chemisorptions of hydrogen ions to the graphene edges and observed by cycling characteristics of the Graphene mesh FETs. Although the hydrogen ion binding to the defects increased the device response to pH change, this binding was found to be irreversible. Howeveer, the irreversible component showed relatively fast decay, almost disappearing after few cycles of exposure to solutions. Similar behavior colud be found in the Graphene FET, but the irreversible component of the response was much smaller. Finally, after complete passivation of the defects, both Graphene and Graphene mesh FETs exhibited only reversible response to pH change, with similar magnitued in the Dirac point shift per pH change. |
