APPLICATIONS OF TECHNOLOGY:
- High speed, low power electronic devices
- Semiconductor devices and fabrication equipment
- Precision control of nanoribbon length, width, and position
- Multiple catalyst candidates
- Potential to introduce graphene band gaps in nanoribbons ~1 nm wide
Berkeley Lab scientist Yuegang Zhang and colleagues have developed a scalable technology for directly growing, with precise control over length, width, and position, graphene nanoribbons narrow enough to open band gaps needed for graphene electronic devices.
The scientists used a chemical vapor deposition (CVD) technique that directly grows graphene on a thin layer of nickel (Ni) or other catalytic metal. Initially, a very thin layer (<20 nm) of metallic catalyst is grown on a substrate, and capped by a layer of material on which graphene cannot grow. The cap and catalyst are subsequently vertically exposed by etching, like cutting a slice of layer cake on a plate. Conventional CVD is used to coat graphene on the exposed catalytic layer, directly above the substrate. When that extremely narrow coated metal layer is removed by wet etching, the graphene coating remains as a nanoribbon (<20 nm) and adheres to the substrate surface.
The technique can produce band gaps of sufficient size to demonstrate field effect transistor switching. A nanoribbon of <10 nm, with a well-defined edge, will open a band gap sufficient for switchable nanoelectronic devices. Using more advanced lithographic techniques with more refined geometries, the Berkeley Lab method should be capable of producing nanoribbons as narrow as 1nm. This research therefore demonstrates for the first time that large-scale fabrication of graphene electronic devices is feasible through the direct growth of graphene nanoribbons on patterned catalytic surfaces.
The extraordinary electronic properties of graphene endow it with great potential for future high speed and low power electronics, but it has a bandgap of zero, limiting its usefulness in the design of switchable electronic devices. Band gaps can be engineered, however, by producing very narrow graphene nanoribbons with clean edges. Unfortunately, the inability to control precisely the length, width, and position of graphene nanoribbons has proven to be a barrier to graphene band gap design. The Berkeley Lab technology overcomes these limitations.
DEVELOPMENT STAGE: Proven principle
STATUS: Issued U. S. Patent 9,061,912. Available for licensing or collaborative research.
FOR MORE INFORMATION:
Martin-Fernandez, I., Wang, D., Zhang, Y. “Direct Growth of Graphene Nanoribbons for Large-Scale Device Fabrication,” Nano Letters, Vol. 12, 6175-6179.
REFERENCE NUMBER: IB-3034