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Nanostructures
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Elaine A. Moore, Lesley E. Smart
Many nanostructures of carbon are known. Carbon Black consists of nanoparticles. Graphene is a single layer of graphite. Bilayer graphene is two sheets of graphene brought close enough to interact. Oxidation of graphene produces graphene oxide in which the graphene layers have functional groups on. Carbon nanotubes (CNT) can be thought of as sections of graphene rolled round to form a tube. CNTs can be single-walled (SWCNT) or multi-walled (MWCNT). Fullerenes are small 3D structures formed of linked pentagons and hexagons of carbon atoms. The most famous is buckminsterfullerene C60.
Introduction of Graphene
Published in Abhay Kumar Singh, Tien-Chien Jen, Chalcogenide, 2021
Abhay Kumar Singh, Tien-Chien Jen
Usually two layers graphene is called bilayer graphene. This can be formed either in twisted configurations such as two layers rotate relative to each other or graphitic Bernal stacked configurations from half atoms in one layer lie on top of half the atoms to other. The bilayer and few-layer (more than two layers) graphene has been classified as pseudo two-dimensional sp2 hybridized carbon structures. The bilayer and few-layer graphene properties are different from monolayer graphene and graphite.
Graphene-Based Single-Electron Transistors
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Bilayer graphene consists of two monolayers of graphene stacked on top of each other. This stacking leads to interlayer hopping, which may result in interlattice coupling, where the strength of this coupling depends on the way graphene is stacked. Here we discuss the most common stacking configuration, that is A – B stacking, as depicted in Figure 11.2a.
Structure of graphene and its disorders: a review
Published in Science and Technology of Advanced Materials, 2018
Gao Yang, Lihua Li, Wing Bun Lee, Man Cheung Ng
Figure 7 illustrates the low-energy DFT 3D band structure and its projection on component close to K point for monolayer, bilayer, and trilayer graphenes and bulk graphite [111]. In the energy spectrum of monolayer graphene, the conduction band and valence band touch at Dirac points, and the electron dispersion near these points is linear. In monolayer graphene, there is no underneath carbon atom for the orbital to interact with, whereas this possibility exists in bilayer graphene, which enables the formation of a zero-energy band. Owing to the presence of massive chiral quasiparticles with parabolic dispersion at low energy [112], the integer quantum Hall effect in bilayer graphene [113] can be even more unusual than that in monolayer graphene. Figure 7(b) shows the four parabolic bands, as the (AB-stacked) bilayer graphene has four atoms in the unit cell. The band structure of bilayer graphene can be tuned by applying an electric field [114,115], providing appropriate substrates [116] or chemical modulations [117,118], which is expected to attract interests in nanoelectronic and nanophotonic applications [119]. From Figure 7(c), the band structure of (ABA-stacked) trilayer graphene seems to be a combination of those of monolayer and (AB-stacked) bilayer. However, trilayer graphene is actually a semimetal with a conductivity that increases with increasing electric field. This behavior significantly differs from that of monolayer and bilayer graphene, which is originated from the presence of a finite overlap between valence and conduction band [120]. Moreover, as effective mass of graphene increases with the increasing layer thickness, trilayer graphene exhibits lower mobility than those of monolayer and bilayer [121]. In general, the low-energy spectrum of FLG with odd number of layers is a combination of one massless Dirac mode and massive Dirac modes per spin and valley, whereas all N modes are massive at low-energies for even number of layers. Therefore, for FLG with N layers (AB stacking), there will be electronlike and holelike parabolic bands and an additional linear energy band (Dirac fermions) around K point [122] if N is odd; Otherwise, there will be only electronlike and holelike parabolic bands around K point. Because of a significant overlap between the conduction and valence bands, FLG thicker than five layers shows a semi-metallic band structure with parabolic-like bands, which is highly similar to that of bulk graphite, as seen in Figure 7(d).