Understanding Surfactant/Graphene Interactions Using a Graphene Field Effect Transistor: Relating Molecular Structure to Hysteresis and Carrier Mobility

摘要

Manipulation of transport hysteresis on graphene transistors and understanding electron transfer betweenngraphene and polar/ionic adsorbates are important for the development of graphene-based sensor devices and nonvolatilenmemory electronics. We have investigated the effects of commonly used surfactants for graphene dispersion in aqueous solutionnon transport characteristics of graphene transistors. The adsorbates are found to transfer electrons to graphene, scatter carrierntransport, and induce additional electron−hole puddles when the graphene is on an SiO2 substrate. We relate the change inntransport characteristics to specific chemical properties of a series of anionic, cationic, and neutral surfactants using a modificationnof a self-consistent transport theory developed for graphene. To understand the effects of surfactant adsorbates trapped on eithernside of the graphene, suspended devices were fabricated. Strong hysteresis is observed only when both sides of the graphene werenexposed to the surfactants, attributable to their function as charge traps. This work is the first to demonstrate the control ofnhysteresis, allowing us to eliminate it for sensor and device applications or to enhance it to potentially enable nonvolatile memorynapplications.