Interplay of Wrinkles, Strain, and Lattice Parameter in Graphene on Iridium

We present results of molecular dynamics simulations of graphene on Cu surfaces. Interactions were modelled with the Charge Optimized Many Body potential, which gives a reasonable though not flawless description of the graphene--Cu system. The interaction between Cu and complete graphene sheets is characterized by an 'averaged out' interaction at a large bonding distance.Many bonding characteristics are indifferent to the details of how the Cu surface atoms are arranged, including the surface orientation and even if the surface is solid or molten. Graphene edges have a strong interaction with the Cu substrates.Systems were modelled at various temperatures, ranging from 0 K to the Cu melting temperature. At high temperature we find that the presence of graphene slightly stabilizes the Cu surface and retards surface melting. After cooling down to room temperature, the Cu substrate is 1.7% smaller than the graphene due to difference thermal expansion coefficients. This leads to the formation of wrinkles in graphene. Single wrinkles experience only small migration barriers and are quite mobile. When multiple wrinkles intersect, they form immobile knots that hinder further movement of the connected wrinkles. The elastic energy of the wrinkles and knots due to bending of the graphene is determined.© 2017 Manuscript version made available under CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ Link to formal publication "Carbon" (Elsevier): https://doi

show abstract

“…Another part of the 1.7% remains as residual strain that remains after wrinkle formation, as observed on Ir surfaces [43,45].…”

Section: Room Temperature Wrinkle Formationmentioning

confidence: 74%

“…5. [42,43,45], Pt [44], Ni [44,46], SiC [47] and, somewhat less clearly recognisable on rougher surfaces, on Cu [48] and…”

Section: Room Temperature Wrinkle Formationmentioning

confidence: 99%

Molecular dynamics simulation of graphene on Cu (1 0 0) and (1 1 1) surfaces

Klaver

Zhu

Sluiter

et al. 2015

Carbon

View full text Add to dashboard Cite

show abstract

“…It has been well documented that the wrinkle formation is to release the increasing built-in stress in graphene sheets, which results from the mismatch in thermal expansion coefficients of the graphene and the substrate. [13][14][15] The number and length of wrinkles continued to increase with the cooling process and reached to the maximum around 100 1C, which then remained constant till room temperature ( Fig. 1a-d).…”

Section: Resultsmentioning

confidence: 91%

“…Among all defects, 1D wrinkles have been frequently observed in graphene structures prepared by various ways. For epitaxial graphene overlayers grown on metals [13][14][15] and SiC surfaces, 16 mismatch in thermal expansion coefficients of the graphene and the substrate causes formation of wrinkles during the cooling process, which have a length ranging from nanometers to micrometers and a height of several nanometers. Part of these line defects align the surface steps and the left run perpendicular to the steps, which relax biaxial thermal stress built in the graphene sheets.…”

Section: Introductionmentioning

confidence: 99%

Enhanced reactivity of graphene wrinkles and their function as nanosized gas inlets for reactions under graphene

Zhang

Cui

et al. 2013

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Formation of wrinkles at graphene/Pt(111) surface was investigated by low energy electron microscopy (LEEM). Reversible wrinkling and unwrinkling of graphene sheets were observed upon cycled heating and cooling treatments, exhibiting a hysteresis effect with the temperature. In situ LEEM studies of graphene oxidation show preferential oxidation of the wrinkles than flat graphene sheets and graphene edges. The function of the wrinkles as one-dimensional (1D) nanosized gas inlets for oxygen and the strain at the distorted sp 2 -hybridized carbon atoms of the wrinkle sites can be attributed to the enhanced reactivity of wrinkles to the oxidation. Meanwhile, wrinkles also served as nanosized gas inlets for oxidation of CO intercalated between graphene and Pt(111). Considering that wrinkles are frequently present in graphene structures, the role of wrinkles as 1D reaction channels and their enhanced reactivity to reactions may have an important effect on graphene chemistry.

show abstract

“…Below R0 domains, where the carbon zigzag rows are aligned with the Ir dense-packed atomic rows, intercalated Co is observed at the Ir atomic steps. Below other rotational domains, intercalated Co is mostly found close to graphene wrinkles, which correspond to local, linear delaminated regions of the graphene sheet induced by strain relief upon cooling the sample after high temperature growth [19,20].…”

mentioning

confidence: 99%

Cobalt intercalation at the graphene/iridium(111) interface: Influence of rotational domains, wrinkles, and atomic steps

Vlaic

Kimouche

Coraux

et al. 2014

Applied Physics Letters

View full text Add to dashboard Cite

Using low-energy electron microscopy, we study Co intercalation under graphene grown on Ir(111). Depending on the rotational domain of graphene on which it is deposited, Co is found intercalated at different locations. While intercalated Co is observed preferentially at the substrate step edges below certain rotational domains, it is mostly found close to wrinkles below other domains. These results indicate that curved regions (near substrate atomic steps and wrinkles) of the graphene sheet facilitate Co intercalation and suggest that the strength of the graphene/Ir interaction determines which pathway is energetically more favorable.In view of potential technological appications, the ability to modify and control the properties of a graphene layer has been a central issue since its discovery [1]. The intercalation of foreign atoms or molecules between a graphene sheet and its substrate often affects the electronic and magnetic properties of the considered interface. For example, the intercalation of noble metals [2,3] or hydrogen atoms [4] can be used to reduce the interaction between graphene and its substrate, and even restore the electronic properties of free-standing graphene, while the intercalation of alkali metals is an efficient mean to control the doping level of graphene [5]. Intercalation of a ferromagnetic transition metal can also enhance the net magnetic moment induced in carbon atoms when graphene is in contact with a magnetic surface [6], and is a promising route to fabricate graphene/ferromagnetic metal hybrid structures with perpendicular magnetic anisotropy [7,8].Understanding where and how a foreign species intercalates below graphene is a challenging task, and different scenarios have been proposed. While oxygen intercalates at the free edges of graphene grown on Ru(0001) [9, 10] and on Ir(111) [11], alkali metals instead may intercalate at the substrate step edges or at boundaries between different rotational domains in graphene/Ni(111) [5] and in graphite [12]. Regarding transition metals, the intercalation mechanism remains elusive. While it has been demonstrated that pre-existing defects in graphene, such as vacancies or pentagon-heptagon pairs, reduce the required energy to trigger intercalation [13,14], several recent experimental works have shown that other mechanisms could be at work. In particular, the formation of atomic defects, not pre-existing in the graphene layer but induced by the contact with a transition metal cluster, with subsequent restoring of the carbon-carbon bonds, has been suggested as a possible way for metal intercalation [14][15][16]. In this work, low-energy electron microscopy [17,18] (LEEM) is used to study cobalt intercalation at moderate annealing temperature (about 125 • C) underneath graphene grown on an iridium (111) surface. Depending on the rotational orientation of the graphene domain, we find Co intercalated at differ-

show abstract

Interplay of Wrinkles, Strain, and Lattice Parameter in Graphene on Iridium

Cited by 144 publications

References 38 publications

Molecular dynamics simulation of graphene on Cu (1 0 0) and (1 1 1) surfaces

Molecular dynamics simulation of graphene on Cu (1 0 0) and (1 1 1) surfaces

Enhanced reactivity of graphene wrinkles and their function as nanosized gas inlets for reactions under graphene

Cobalt intercalation at the graphene/iridium(111) interface: Influence of rotational domains, wrinkles, and atomic steps

Contact Info

Product

Resources

About