Clarification of Doping Dynamics in Oxygen Adsorption on a Graphene‐Based Field‐Effect Transistor

Monolayer graphene is a 2D material in which all constituent atoms are located on the surface, allowing for significant changes in electronic properties through molecular adsorption, making graphene a promising material for applications in chemical sensors. Particularly, hole doping in graphene‐based field‐effect transistors (FETs) upon oxygen adsorption has been extensively studied. However, the hole‐doping dynamics, including the role of atmospheric water, remain unclear. Herein, the gate voltage dependence of the speed of hole doping by oxygen is investigated using graphene on a parylene‐coated hydrophobic substrate under strictly controlled humidity conditions. Herein, it is experimentally demonstrated that the doping dynamics in oxygen adsorption on a graphene FET are understood by an electrochemical doping mechanism involving water.