Sep 23, 2008
Writing tool expands graphene coverage
Graphene's remarkable properties have been dazzling scientists for years, but to grab industry's attention the community needs to come up with a way of processing the material on a much larger scale. Researchers at the New Jersey Institute of Technology (NJIT) have taken up the challenge and are using a modified chemical-mechanical-polishing (CMP) technique to cover areas measuring hundreds of microns squared with a monolayer of carbon atoms.
"Large-area coverage means that one day we may be able to cover an entire wafer with this unique material to create high-speed and perhaps flexible circuitry," Haim Grebel, director of NJIT's electronic imaging centre told nanotechweb.org. "In my opinion though, the ability to fabricate suspended structures could turn out to be more important."
In their current work, Grebel and his graduate student, Amrita Banerjee, have reported a dramatic enhancement of infrared and Raman signals for biomolecules residing on graphenated screens (see image).
To pattern a substrate with graphene, the team first lowers a highly orientated pyrolitic graphite (HOPG) ingot onto the surface. Next, a computer-operated 2D translation stage moves the substrate below the HOPG ingot to write the desired feature.
Initially, the film consists of multilayered graphite in the form of connected islands. By annealing the material at 800–900 °C for three hours, the researchers found that they could recover any stacking faults and obtain a highly crystalline monolayer on solid and perforated substrates alike. Surfaces investigated so far include silicon, anodized aluminium oxide and screens made of copper.
In its simplest form, the deposition method can be considered as a lapping process and the group plans to offer the apparatus as a stand-alone tool by modifying existing CMP systems.
Grebel recognizes that covering a 12 or 18 inch wafer with a monolayer thick, two-dimensional crystal represents a big challenge, but the rewards are high thanks to graphene's high thermal conductivity, remarkable mechanical strength and two dimensional electronic properties.
The researchers presented their work in Nanotechnology.
About the author
James Tyrrell is editor of nanotechweb.org.