Cutting nanodisks in graphene down to 20 nm in diameter.

A direct focused He+ beam direct machining is presented to fabricate solid-state nano-disk at the surface of a graphene multilayer micro-flake deposited on an Au/Ti/sapphire surface. At irradiation doses larger than 5.0×1017 ions/cm2 and with a beam size well below 1 nm, graphene disks down to 20 nm in diameter have been machined with for nano-disk down to 50 nm in diameter, a central hole for preparing the positioning of a rotation axle. The local heat generated by this irradiation is inducing a partial graphene amorphization and deformation, leading to a complete graphene nano-disk vaporization at doses larger than 5×1018 ions/cm2. A dry transfer printing technique followed by a graphene surface cleaning was used to transfer the nano-disks from its initial surface to a fresh and clean surface. Tapping mode atomic force micrograph has been recorded to follow the vaporization as a function of the He+ dose to confirm the graphene solid-state nano-disk fabrication limit to about 20 nm with this process.