The Effect of Atomic-Scale Defects and Dopants on Graphene Electronic Structure

Abstract

Graphene, being one-atom thick, is extremely sensitive to the presence of adsorbed atoms and molecules and, more generally, to defects such as vacancies, holes and/or substitutional dopants. This property, apart from being directly usable in molecular sensor devices, can also be employed to tune graphene electronic properties.Here we briefly review the basic features of atomic-scale defects that can be useful for material design. After a brief introduction on isolated p z defects, we analyse the electronic structure of multiple defective graphene substrates, and show how to predict the presence of microscopically ordered magnetic structures. Subsequently, we analyse the more complicated situation where the electronic structure, as modified by the presence of some defects, affects chemical reactivity of the substrate towards adsorption (chemisorption) of atomic/molecular species, leading to preferential sticking on specific lattice positions. Then, we consider the reverse problem, that is how to use defects to engineer graphene electronic properties. In this context, we show that arranging defects to form honeycomb-shaped superlattices (what we may call "supergraphenes") a sizeable gap opens in the band structure and new Dirac cones are created right close to the gapped region. Similarly, we show that substitutional dopants such as group IIIA/VA elements may have gapped quasiconical structures corresponding to massive Dirac carriers. All these possible structures might find important technological applications in the development of graphene-based logic transistors.

A few simple rules governing hydrogenation of graphene dots

“…This is done here by complementing the DFT data with those obtained by using more accurate correlated wavefunction techniques. En passant, we briefly discuss the magnetic properties of pristine and hydrogenated PAHs, which turn out to be well predicted by Lieb's theorem 31 , in agreement with previous studies on triangularly and hexagonally shaped GDs 32 and other defective graphenic structures 27,28 .…”

“…due to the presence of staggered midgap states). This is similar to graphene 27,28 , where these states form the basis for a preferential sticking mechanism 29,30 forming para-dimers (i.e. two H atoms on opposite corners of the same ring).…”

“…The latter is also the position of the Fermi level with one electron per site (half-filling), and for this reason the above symmetry is also called electron-hole symmetry. In conjunction with the spatial symmetry, the presence of such symmetry is at the origin of the conically shaped band structure of graphene close to the Fermi level 28 , with interesting consequences on band-engineering 33,34 and on the chemical reactivity 27 . Here, to clarify the connection with chemical reactivity, we focus on some simple results on the shape of low energy (i.e.…”

Atomic-scale characterization of nitrogen-doped graphite: Effects of dopant nitrogen on the local electronic structure of the surrounding carbon atoms

“…Note that the feature of three-fold propagation in Fig. 3(e) is similar to the case of a single-atom vacancy in graphite [30,[41][42][43][44], though the localization is much weaker for the pyridinic-N.…”

Critical wavefunctions in disordered graphene

“…For doped graphene, is clear that the p = 2 IPR can be fitted with a line, which suggests a non-localized, power-law behavior, which is the main result of this work. Near the Dirac energy, it is known that resonant states can appear at an energy E r obtained by solving the corresponding Lifshitz equation, using the pure graphene Green's function [26,27]. These resonant states are well characterized when ε is bigger than the bandwidth, and leads to a tendency for increased localization at the band center due to frustration effects [28].…”