Dynamic Gate Control of Aryldiazonium Chemistry on Graphene Field-Effect Transistors

Graphene field-effect transistors (GFETs) are promising candidates for sensor applications, but controlled functionalization of their surface is critical to ensure specific interactions with the chosen analyte. Among functionalization strategies, covalent adducts are most likely to ensure bond stability during multiple flow cycles. We demonstrate a state-of-the-art method using the gate electrode to precisely modulate and monitor aryldiazonium functionalization on parallel graphene devices. We first show that spontaneous functionalization of GFETs is heterogeneous with a low overall yield using characterization techniques such as on-device electrical measurements and Raman spectroscopy. We then propose to tune the gate voltage to dynamically enable or suppress the reaction and obtain a high homogeneity in our results. We also monitor, control, and analyze the functionalization kinetics in real-time. The mechanism for our approach is based on the Fermi level modulation of graphene, analogous to chemical, substrate-based, or electrochemical doping, but it has the practical advantage of being compatible with chip and device geometries. This work illustrates how we can utilize FET platforms to gain further insights on surface reactions on nanomaterials in real-time.