Implantation and Atomic-Scale Investigation of Self-Interstitials in Graphene

Abstract

Crystallographic defects play a key role in determining the properties of crystalline materials. The new class of two-dimensional materials, foremost graphene, have enabled atomically resolved studies of defects, such as vacancies, 1-4 grain boundaries, 5-7 dislocations, 8,9 and foreign atom substitutions. 10-14 However, atomic resolution imaging of implanted selfinterstitials has so far not been reported in any three-but also not in any two-dimensional material. Here, we deposit extra carbon into single-layer graphene at soft landing energies of ∼1 eV using a standard carbon coater. We identify all the self-interstitial dimer structures theoretically predicted earlier, 15-17 employing 80 kV aberration-corrected high-resolution transmission electron microscopy. We demonstrate accumulation of the interstitials into larger aggregates and dislocation dipoles, which we predict to have strong local curvature by atomistic modeling, and to be energetically favourable configurations as compared to isolated interstitial dimers. Our results contribute to the basic knowledge on crystallographic defects, and lay out a pathway into engineering the properties of graphene by pushing the crystal into a state of metastable supersaturation.

On-surface synthesis of a nitrogen-embedded buckybowl with inverse Stone–Thrower–Wales topology

“…The ISTW defect differs in the topology of the non-hexagonal rings from the more prevalent STW defect, which consists of a pair of joined heptagonal rings in between a pair of pentagonal rings 47 – 50 . So far, the ISTW defect has been experimentally demonstrated to occur on single layer graphene under a transmission electron microscope (TEM) either via high-energy electron irradiation, causing removal of atoms and subsequent reconstruction of the carbon lattice around vacancies 51 , or low-energy landing of carbon atom(s) and their subsequent incorporation as dimers in the sp 2 framework 52 . While promising, the short lifetime of such defects under the electron beam of a TEM and the random nature of generation with no control over spatial location precludes their application in nanoscale defect engineering of graphene for device applications.…”

Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects

“…[28]. The defect in Figure 1a is produced by carbon deposition, as will be described in detail in a separate paper [29]. The MoSe 2 sample was produced by molecular beam epitaxy and transferred on to Pelco holey silicon nitride TEM grids (a detailed study on this sample will be presented also in a separate article [30]).…”

Oxidation Behaviors of Two‐dimensional Metal Chalcogenides

“…In experiments, defects are quite common in 2D materials, such as self‐interstitials, vacancies, and grain boundaries, which are significant for the material's properties . For example, point defects, antisite defects, dislocations and vacancy complexes are commonly observed in graphene, silicone and TMDs, and they can lead to modification of the oxidation behaviors and hence change the physical and chemical properties of 2D materials …”