Modification of Defect Structures in Graphene by Electron Irradiation: Ab Initio Molecular Dynamics Simulations

Abstract

Defects play an important role on the unique properties of the sp2-bonded materials, such as graphene. The creation and evolution of monovacancy, divacancy, Stone-Wales (SW), and grain boundaries (GBs) under irradiation in graphene are investigated using density functional theory and time-dependent density functional theory molecular dynamics simulations. It is of great interest that the patterns of these defects can be controlled through electron irradiation. The SW defects can be created by electron irradiation with energy above the displacement threshold energy (T d, ∼19 eV) and can be healed with an energy (14–18 eV) lower than T d. The transformation between four types of divacanciesV2(5–8–5), V2(555–777), V2(5555–6–7777), and V2(55–77)can be realized through bond rotation induced by electron irradiation. The migrations of divancancies, SW defects, and GBs can also be controlled by electron irradiation. Thus, electron irradiation can serve as an important tool to modify morphology in a controllable manner and to tailor the physical properties of graphene.

Quasi-Two-Dimensional SiC and SiC2: Interaction of Silicon and Carbon at Atomic Thin Lattice Plane

“…The potential energy of system decreases continuously as synthesis proceeds, which demonstrates that the SiC monolayer is thermal dynamically stable. Corresponding to the structure evolvement shown in Figure 1b 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9 in analogy with the modification of defect structures in graphene sheet 41 , the irregular rings, which are actually defects, are healed gradually as the synthesis proceeds. Some energy barriers should be overcome for transformation of irregular polygonal rings into the regular SiC rings.…”

Highly Itinerant Atomic Vacancies in Phosphorene

“…39 The E b for the transformations between the low energy DVs (585, 555-777 and 5556-6-7777) are significant (greater than 5 eV). The large barriers suggest that DVs in graphene are locked in a specific position and orientation at RT once formed, and the thermally activated motion of DV requires an extremely high temperature of 3000 K. 40,41 In contrast, our results show that transitions of DVs in phosphorene have much lower E b ranging from 0.44 to 1.83 eV (estimated hopping rate from 2.0× 10 9 to 6.8×10 -3 per second at 600 K) for the four low energy DVs (5757-A, 585-A, 555-777 and 5555-6-7777-A), implying a much enhanced thermal activity even at RT. Interestingly, these E b for DV transitions are comparable to those of MV motion.…”

Structure Identification in High-Resolution Transmission Electron Microscopic Images: An Example on Graphene

“…Investigations and theoretical results Wang et al, 2012) predict a connection between the microscopic structure of graphene and its macroscopic properties. These properties are related to the regular two-dimensional (2D) honeycomb lattice in which carbon atoms are arranged in graphene.…”