Adsorbates on Multilayer Graphene Surface: Morphology, Distribution and Electrical Properties

Here an adsorption phenomenon on the surface of multilayer graphene in air atmosphere over time was studied. We found that after 2~3 months, some unknown adsorbates absorbed on the surface of graphene. The adsorbate films (~2nm) have no regular shape and most of them distribute on the flat graphene surface, some along the wrinkle or around a nanoparticle. The longitudinal conductivity of the multilayer graphene is substantially increased (at least 30 times) owing to the presence of the adsorbates. A reliable method to remove the adsorbates is proposed using a visible laser. This work may open up the potential application of adsorbates in graphene devices, and a new field of reliability of graphene devices.