10-04 :: April 2010

nanotimes

News in Brief

41

To make a graphene thin film, Berkeley researchers (a) evaporated a thin layer of copper on a dielectric surface; (b) then used CVD to lay down a graphene film over the copper. (c) The copper dewets and eva- porates leaving (d) the graphene film directly on the dielectric substrate. © Yuegang Zhang/LBL

(a) Optical image of a CVD graphene film on a copper layer showing the finger morphology of the metal; (b) Raman 2D band map of the graphene film between the copper fingers over the area marked by the red square on left.© Yuegang Zhang/LBL

“Further improvement on the control of the de- wetting and evaporation process could lead to the

direct deposition of patterned graphene for large- scale electronic device fabrication, Zhang says.

“This method could also be generalized and used to deposit other two-dimensional materials, such as boron-nitride.”

Even the appearance of wrinkles in the graphene films that followed along the lines of the dewetting shape of the copper could prove to be beneficial in the long-run. Although previous studies have indica- ted that wrinkles in a graphene film have a negative impact on electronic properties by introducing strains that reduce electron mobility, Zhang believes the wrinkles can be turned to an advantage.

“If we can learn to control the formation of wrin- kles in our films, we should be able to modulate the resulting strain and thereby tailor electronic proper- ties,” he says.

“Further study of the wrinkle formation could also give us important new clues for the formation of gra- phene nanoribbons.”

Ariel Ismach, Clara Druzgalski, Samuel Penwell, Adam Schwartzberg, Maxwell Zheng, Ali Javey, Jeffrey Bokor and Yuegang Zhang: Direct Chemical Vapor Deposition of Graphene on Dielectric Surfaces, In: Nano Letters ASAP, April 2, 2010, DOI:10.1021/nl9037714: http://dx.doi.org/10.1021/nl9037714