Non-invasive transmission electron microscopy of vacancy defects in graphene produced by ion irradiation

Abstract

Irradiation with high-energy ions has been widely suggested as a tool to engineer properties of graphene. Experiments show that it indeed has a strong effect on graphene's transport, magnetic and mechanical characteristics. However, to use ion irradiation as an engineering tool requires understanding of the type and detailed characteristics of the produced defects which is still lacking, as the use of high-resolution transmission microscopy (HRTEM) -the only technique allowing direct imaging of atomic-scale defects -often modifies or even creates defects during imaging, thus making it impossible to determine the intrinsic atomic structure.Here we show that encapsulating the studied graphene sample between two other (protective) graphene sheets allows non-invasive HRTEM imaging and reliable identification of atomicscale defects. Using this simple technique, we demonstrate that proton irradiation of graphene produces reconstructed monovacancies, which explains the profound effect that such defects have on graphene's magnetic and transport properties. This finding resolves the existing uncertainty with regard to the effect of ion irradiation on the electronic structure of graphene.Knowing the detailed microscopic structure of atomic-scale defects in graphene, such as vacancies or grain boundaries, is crucially important for understanding and potentially controlling their effect on electronic and spin transport, mechanical strength, chemical reactivity and thermal conductivity of

Preferential antiferromagnetic coupling of vacancies in graphene onSiO2: Electron spin resonance and scanning tunneling spectroscopy

“…Notice that MD simulations exclusively find single vacancies after Ar + bombardment at 50 eV of monolayer graphene [68] and again that the TEM data imply that the single vacancies are immobile [58]. Indeed, the defects exhibit a peak in dI/dV spectroscopy exclusively around E F up to ion fluences of 1/(nm 2 ) as expected for single vacancies [ Fig.…”

Significance of interface barrier at electrode of hematite hydroelectric cell for generating ecopower by water splitting

“…The strain is relaxed by formation of structural defects, and morphology of these defects is strongly dependent on growth kinetics . Planar surface defects and vacancy defects exhibit Moire fringes . Existence of defects in the form of vacancy defects, fault zones, and misfit dislocations is visibly marked by white arrows (Figure D,E) .…”

Defects in Graphene: Generation, Healing, and Their Effects on the Properties of Graphene: A Review

“…Modern electron microscopes with aberration-corrected condensers allow focusing an electron beam onto a spot of approximately 1 Å in diameter thereby creating vacancies with almost atomic selectivity [30] . Another physical method which has been used for defect production in graphene is ion irradiation [31][32][33][34][35] . It can be used to selectively produce certain defects or to pattern and cut graphene with a precision down to 10 nm utilizing a focused ion [36,37] .…”