Measuring the Double Layer Capacitance of Electrolyte Solutions for a Graphene Field Effect Transisitor

When operating graphene field effect transistors (GFETs) in fluid, a double layer capacitance (Cdl) is formed at the surface. In the literature, numbers from experiments using metal electrodes are quoted to calculate the Cdl. This work seeks to characterize the double layer capacitance of a GFET independent of the metal electrode theory. A unique method for determining the Cdl is implemented for three electrolytes and one ionic fluid, and the results are compared to the generally quoted metal electrode values. A significant difference is found between the metal electrode theory and our results, suggesting that the independent method used gives a more accurate figure for GFET surfaces