Fabricating Defect-Free Graphene

February 8th, 2013 by

Researchers at a university in the UK have overcome a key problem of growing graphene without the defects that weaken it and prevent electrons from flowing freely within it when using chemical vapor deposition. With the previous methods, tiny flakes of graphene form with random orientations, leaving defects or seams between flakes that grow together. The discovery reveals how these graphene flakes, known as domains, can be lined up by manipulating the alignment of carbon atoms on a relatively cheap copper foil – the atomic structure of the copper surface acts as a guide that controls the orientation of the carbon atoms growing on top of them. The combination of control of this copper guide and the pressure applied during growth makes it possible to control the thickness of these domains, the geometry of their edges, and the grain boundaries where they meet that act as obstacles to the smooth progress of electrons necessary to create efficient graphene-based electrical and electronic devices. Current methods of growing flakes of graphene often suffer from graphene domains not lining up. With the new fabrication technique, it is possible to produce large sheets of graphene where these domains are well-aligned, which will create a neater, stronger, and more electron-friendly material. In principle the size of the sheet of graphene that can be created is only limited by the size of the copper base sheet. The researchers have also shown that it is also possible using the new technique to selectively grow bilayer domains of graphene, which are of particular interest for their unusual electrical properties.