ABSTRACT
Graphene is a one-atom thick sheet of sp2-hybridized carbon atoms arranged in a honeycomb lattice, and thereby the thinnest possible material in Nature. Since the middle of the 20th century, graphene has been studied theoretically as the building block of carbon allotropes. The hybridized s and p orbitals form strong directional covalent bonds leading to a large number of different allotropes. Another extraordinary feature of graphene is that there is no energy gap between conduction and valence bands at Dirac points. As such, graphene can be considered a semiconductor with no bandgap, or a semimetal with no band overlap. Graphene shows exotic electronic properties and may outperform state-of-the-art silicon in many applications due to its exceptional properties such as large carrier motility, high carrier concentration, high thermal conductivity, and atomically thin planar structure. However, the application of large-area graphene is limited for integrated circuits due to the lack of bandgap and the need for only narrow stripes of graphene.
