Controllable nano-friction of graphene surface by fabricating nanoscale patterning based on atomic force microscopy

Friction-controlled graphene has great potential as a solid lubricant in micro/nano electromechanical systems. In this work, the conductive atomic force microscope was used to conduct oxidation etching on the graphene surface to produce different nanoscale patterns. The frictional properties of graphene nanoscale patterns were compared under different etching parameters, and the degree of oxidation of the etching patterns was analyzed by Scanning Kelvin Probe Microscopy. The results indicated that the degree of graphene oxidation can be controlled by changing the tip voltage, load and thickness so that graphene forms stable, adjustable oxidation point, line and nanometer patterns on the Au/SiO₂/Si substrate. The diameter of oxidation point and width of oxidation line increased with the increase of voltage. The continuity and uniformity of nanometer patterns was improved by Increasing the thickness of graphene. The friction increased with the increase of tip voltage, which was attributed to the increase of meniscus force and electrostatic force. These nanostructures can precisely regulate nano-friction of graphene surface. The realization of the processing of nanoscale patterns and the adjustment of nano-friction characteristics provides a new idea and method for the study of electrical friction behavior of graphene in micro/nano electromechanical systems and the preparation of nano-devices with patterned surfaces.