Tailoring properties of graphene with vacancies

Abstract

The influence of vacancy defects on the electronic and phonon properties of graphene is studied with the models based on a unit cell of 180 carbon atoms and of 1, 2, 3, 6, and 24 vacancies. Ordered, with one defect per unit cell, and non‐ordered (randomly arranged) vacancies are calculated with first‐principle and molecular dynamics methods. Randomly oriented vacancies lead to a creation of characteristic V1(5‐9) defects and the amorphization of graphene with different rings. Electronic and phonon densities of states are analyzed. The switching of the electrical conductivity from metal to semiconductor type is observed when increasing the defect sizes from a single vacancy to large clusters. The characteristic phonon modes are found in all these cases for their future experimental identification. Novel types of devices are proposed via doping of defective graphene.

Electronic Structure of Nitrogen-Doped Graphene in the Ground and Core-Excited States from First-Principles Simulations

“…A benzene ring is missing, leaving six carbons with dangling sp 2 bonds and local magnetism. This model had been theoretically considered, − and it is the most stable vacancy that widely appears on neutron-irradiated graphite surfaces . On the basis of the 6V-defected graphene, two typical doping configurations with pyridinic and pyrrolic N-dopants were considered for NEXAFS spectra.…”

Cooperative topological accumulation of vacancies in honeycomb lattices

“…See for example in Figure 3 the 3C-3D plateau corresponding to the 24 ≤ N n v ≤ 47 interval in which the topological potential Ξ ρE remains flat, approximately at the ρ E (Nv=24) = 1.1621 level although vacancy concentration almost doubles by passing from 3% to 5.9%, forming nanometric-sized defective regions in the lattice (see Figure 4). According to [21], such a kind of large randomly oriented clusters of vacancies may lead to graphene amorphization and largely influenced by the electronic features of the carbon atoms and the chemical dopants possibly present. Lattice descriptor ρ E sharply grows when also hexagon H remains with a single dandling bonds ( Figure 3E step) and new multiple vacancies ( Figure 3F step) are distributed along quasi-linear configurations in the layer.…”

Ab initio calculations of ideal and defective bismuth telluride nanotubes

“…The geometries are optimized with a force tolerance of 0.05 eV Å −1 . This value was shown to be enough to represent relaxed systems at temperature of 0 K .…”

“…They were extensively studied both experimentally and theoretically . Recently, it was possible to exfoliate a quintuple layer into thinner ones, namely atomically thin two‐layered (or bilayer), like graphene , and three‐layered (or trilayer) sheets having high electrical conductivities . Weak covalent interactions between bilayer and trilayer and much stronger interactions inside bilayer (trilayer) open the way to create nanotubes by rolling up of bulk fragments.…”