Sub-10 nm patterning by focused He-ion beam milling for fabrication of downscaled graphene nano devices

• We report a novel, hybrid fabrication process for sub-10 nm patterning of graphene.
• It is a combination of conventional e-beam lithography and He-ion milling.
• He-ion milling is used to pattern the graphene flakes with intricate DQD devices.
• We demonstrate the first electrically characterized He-ion beam patterned graphene device.
• This method could pave the way to more detailed study of graphene quantum devices.

In this work, a novel hybrid fabrication method for graphene quantum dot devices with minimum feature sizes of ∼3 nm and high yield is described. It is a combination of e-beam lithography and direct milling with the sub-nm focused helium ion beam generated by a helium ion microscope. The method is used to fabricate graphene quantum dot devices contacted with metal to allow electrical characterization. An annealing step is described that reduces hydrocarbon contamination on the sample surface and allows complete removal of graphene by the helium ion beam and therefore successful isolation of side gates. The electrical characterization of the final device demonstrates the successful fabrication of the first electrically characterized He-ion beam patterned graphene device. The highly controllable, fine scale fabrication capabilities offered by this approach could lead to a more detailed understanding of the electrical characteristics of graphene quantum devices and pave the way towards room-temperature operable graphene quantum dot devices.

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