Graphene field-effect transistors (FETs) have attracted tremendous attention owing to the single-atomic-layer thickness and high electron mobility for potential applications in next-generation electronics. With regards to switching methodology, the electric-field-induced metal-insulator transition offers a new strategy to produce a large on/off current ratio through reversible electrochemical hydrogenation of the graphene channels. Therefore, the performance of such electrochemical graphene FETs greatly relies on the kinetics of hydrogenation reaction. Here, we show that the switching time can be systemically controlled by the applied gate voltages and geometries of graphene channels. The turn-on and turn-off time display an exponential dependence on the gate voltages, manifesting the dominated Tafel-form kinetics of hydrogenation reaction in a two-dimensional limit. Moreover, the turn-off time is inversely proportional to the channel width but independent of the length, while the turn-on time relies on both the width and length, as well as the off-state gate voltage and duration. Our work improves the response time to the magnitude of tens of microseconds and advances the application of graphene-based electronic devices.
Keywords: electrochemical; field-effect transistors; graphene; hydrogenation; on/off switching.