Spatial control of defect creation in graphene at the nanoscale

Abstract

Defects in graphene alter its electrical, chemical, magnetic and mechanical properties. The intentional creation of defects in graphene offers a means for engineering its properties. Techniques such as ion irradiation intentionally induce atomic defects in graphene, for example, divacancies, but these defects are randomly scattered over large distances. Control of defect formation with nanoscale precision remains a significant challenge. Here we show control over both the location and average complexity of defect formation in graphene by tailoring its exposure to a focussed electron beam. Divacancies and larger disordered structures are produced within a 10×10 nm 2 region of graphene and imaged after creation using an aberrationcorrected transmission electron microscope. some of the created defects were stable, whereas others relaxed to simpler structures through bond rotations and surface adatom incorporation. These results are important for the utilization of atomic defects in graphene-based research.

Structure of graphene and its disorders: a review

“…However, in most cases the properties of graphene are supposed to be tailored for satisfying different requirements in industries. Tuning properties of graphene can be realized by several defects modulations approaches, including particle irradiation [326–328], thermal annealing [329,330], chemical reaction [331,332] and strain treatment [333,334], as summarized in Table 2.…”

“…Typically, irradiating graphene with energetic particles, such as ions [326,336–338] or electrons [328,339], can effectively create point defects (mostly vacancies), due to the ballistic ejection of carbon atoms. Carbon atoms that gain sufficient energy (approximately 18–20 eV) from the irradiating beams may be sputtered away from graphene, get adsorbed on the sheet or migrate on the surface as adatoms.…”

“…(b) D/G’ intensity ratios as functions of Ar+ ion irradiation fluence (in 10 13  ions/cm 2 ) [326]. Schematics of the beam profile used in the three principle stages [328]: (c) a broad beam used to image graphene before defect formation, (d) a focused beam with a high current density used to form defects and (e) a broad beam used to image graphene after defect formation. (f) Creation of the defects can be explained by atom ejection and reorganization of bonds via bondrotation [339] (reused with permissions from [326] Copyright © 2012, John Wiley and Sons, [328] Copyright © 2012, Springer Nature, and [339] Copyright © 2011 American Physical Society). …”

“…Alternatively, it is possible to in situ monitor the defects fabrication at atomic level by using an aberration-corrected TEM [328] following three principle steps (see Figure 17(c–e)): a broad electron beam used to image the pristine graphene with relatively low beam current density of ~ 10 5  e −1  nm −2  s −1 , a focused beam with high current density (10 8  e −1  nm −2  s −1 ) employed to create defects, and a broad beam with low current density adopted to observe the formed disorders on graphene. It is evidenced from the electron irradiation experiments that both the location and average complexity of defect formation in graphene could be controlled by tailoring the electron beam current density and the exposure time.…”

Diffraction and near-zero transmission of flexural phonons at graphene grain boundaries

“…The grain boundaries commonly consist of dislocations in the form of pentagon-heptagon defect pairs, and cause out-of-plane buckling of the graphene sheet [9][10][11][12][13][14][15][16]. Recent experimental studies show that dislocations can be introduced into pristine graphene using a focused electron beam [13,14,[17][18][19], suggesting the possibility of adjusting the properties of the material.…”