Synopsis: Identification by Bonds

Electron microscopy reveals the bond configurations of individual silicon impurities adsorbed on graphene.
Synopsis figure
W. Zhou et al., Phys. Rev. Lett. (2012)

Silicon is one of the most common impurities to adsorb on graphene grown by chemical vapor deposition, and significantly affects graphene’s transport properties. Understanding the chemistry of these impurities is thus important, especially if the desire is to integrate graphene with silicon electronics. So far, no techniques have been able to characterize individual silicon-carbon bonds. Now, writing in Physical Review Letters, Wu Zhou at Vanderbilt University, Tennessee, and collaborators demonstrate they are able to deduce the nature of these bonds by combining several electron microscopy techniques.

Zhou et al. studied the energy loss of electrons aimed at a graphene surface containing silicon impurities. Similar experiments did this before, but lacked the signal strength to accurately analyze the bonds. Zhou et al. overcame this difficulty by combining their study with annular dark-field imaging, a method that excludes the unscattered beam to obtain images in which intensity provides chemical information about the sample.

By comparing their spectroscopic data with density-functional-theory calculations, they can easily tell the difference between silicon bonded to four or three carbon atoms, raising the prospect that the combination of these different electron microscopy techniques could allow the study of chemical bonding at the single impurity level in other two-dimensional materials. – Daniel Ucko


More Features »


More Announcements »

Subject Areas


Previous Synopsis

Next Synopsis

Quantum Physics

No Free Lunch, or Measurements

Read More »

Related Articles

Synopsis: Dirac Cones in Boron’s Version of Graphene
Materials Science

Synopsis: Dirac Cones in Boron’s Version of Graphene

A one-atom-thick sheet of boron atoms exhibits Dirac cones, marking the first time this electronic property has been found in a material lacking a graphene-like crystal structure.  Read More »

Synopsis: Graphene’s Elegant Optics Explained

Synopsis: Graphene’s Elegant Optics Explained

Theoretical calculations anchor graphene’s simple optical absorption in its two-dimensional structure instead of its cone-shaped energy bands. Read More »

Synopsis: A New Way to Make Graphene

Synopsis: A New Way to Make Graphene

The addition of a rapid-cooling step to the epitaxial growth of graphene on silicon carbide can yield higher-quality graphene sheets. Read More »

More Articles