Invention:
Isotopically-enriched graphene and isotope junctions are epitaxially grown on a catalyst substrate using a focused carbon ion beam technique. The focused carbon ion beam is filtered to pass substantially a single ion species including a single desired carbon isotope. The ion beam and filtering together provide a means to selectively isotopically-enrich the epitaxially grown graphene from given carbon precursor and to selectively deposit graphene enriched with different carbon isotopes in different regions.
Background:
Graphene is a one-atom-thick planar sheet of sp2 -bonded carbon atoms that are densely packed in a honeycomb, hexagonal crystal lattice. Graphene is a basic building block for graphitic materials of all other dimensionalities. Graphene can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite. Graphene has rather remarkable properties. Graphene is stable, chemically inert, and crystalline under ambient conditions. It is a semimetal in that its conduction and valence bands just meet at discrete points in the Brillouin zone. An electron in graphene has an effective mass of zero and behaves more like a photon than a conventional massive particle. Finally, graphene can carry huge current densities--about 108 A/cm2, roughly two orders of magnitude greater than copper. Graphene is a candidate for replacing silicon as a basis for faster, more powerful electronics. Graphene nanoribbons (GNRs) are essentially single layers of graphene that are cut in a particular pattern to give it certain electrical properties.
Advantages:
- Method to grow single or multilayer graphene of a single carbon isotope
- Method to grow graphene isotope heterojunctions in which distinct regions of 12C or l3C are grown adjacent to one another
Applications:
- Transistors that operate at higher frequency
- Low cost displace screens in mobile devices
- Graphene transistors
- Transparent conducting electrodes
Status: issued U.S. Patent #8,647,436
