Mechanical fabrication of graphene devices using focused-ion beam: Deposition and milling

Graphene, due to its material stability, mechanical strength, unique band structure and excellent electrical properties, holds great promise for future nanoscale electronic devices. Here, we report a novel mechanical fast-prototyping method to fabricate graphene-based electronic structures on few-layer graphene (FLG) using focused-ion beam (FIB). FIB is a versatile tool and FIB-assisted deposition and milling processes feature mask-free patterning, quick turnaround time as well as high precision. Specifically, in this study, the parameters of FIB are well controlled. The platinum wire, which is induced from the gaseous precursors by the fine focused gallium ions of low energy, is conveniently deposited on the substrate to connect FLG. The measured channel resistance of around 50 kΩ indicates good electrical contact between platinum wire and FLG. With the computer controlled alignment and patterning, the accuracy of deposition and milling can be as high as 15-20 nm. For the milling process, 2-D ribbon structures can be easily produced by milling the patterned area, followed by an annealing process. Raman spectra are used to examine the quality of graphene after the FIB and annealing processes.