| Motivated by the interest in graphene as a chemical sensor, this thesis presents an analysis of how the conductance of a fabricated graphene field effect transistor can be modulated by the presence of water vapour and oxygen in the substrate of the device. The fabrication process of a graphene field effect transistor consists of optically locating a graphene monolayer on an oxidized silicon substrate, and contacting it with metal electrodes using electron-beam lithography. The conductance of graphene FETs at ambient conditions, vacuum, and exposed to different gases, is measured to investigate the connection between conductance modulation and the electrochemistry taking place in the substrate of the device and on the surface of the graphene flake. This study supports the possibility of using graphene FETs as chemical sensors since a relationship between added adsorbates and the symmetry of the Dirac like conductance can be drawn.;Keywords: Graphene, graphene band structure, graphene FETs, graphene nanofabrication, conductance modulation, graphene sensors, electrochemistry. |
