A direct look at graphene

Michael Crommie, a physicist of Berkeley Lab’s Materials Sciences and Physics Department, led a study of how electrons and holes respond to a charged impurity. These results support the theory that interactions between electrons are critical to graphene’s extraordinary properties. Strength, flexibility and charge-transmission speed is what makes graphene a special electrical conductor for a host of applications such as the ultrafast transistors. With a specially equipped scanning tunneling microscope in ultra-high vacuum, Crommie and his colleagues examined gated devices consisting of a graphene layer deposited atop boron nitride flakes which were themselves placed on a silicon dioxide substrate. This study verified the predictions that electrons in graphene are pulled into a positively-charged impurity too weekly, and found the value for the dielectric to be small enough to indicate that electron-electron interactions contribute significantly to graphene properties.