Strain-activated edge reconstruction of graphene nanoribbons

Abstract

The edge structure and width of graphene nanoribbons (GNRs) are crucial factors for the electronic properties. A combination of experiment and first-principles calculations allows us to determine the mechanism of the hexagonhexagon to pentagon-heptagon transformation. GNRs thinner than 2 nm have been fabricated by bombardment of graphene with high-energetic Au clusters. The edges of the GNRs are modified in situ by electron irradiation. Tensile strain along the edge decreases the transformation energy barrier. Antiferromagnetism and a direct band gap are found for a zigzag GNR, while a fully reconstructed GNR shows an indirect band gap. A GNR reconstructed on only one edge exhibits ferromagnetism. We propose that strain is an effective method to tune the edge and, therefore, the electronic structure of thin GNRs for graphene-based electronics.

Long triple carbon chains formation by heat treatment of graphene nanoribbon: Molecular dynamics study with revised Brenner potential

“…Directions of reactions are indicated by arrows.First let us compare the energetic characteristics of local structures at the edge of narrow ZGNRs obtained here by the DFT calculations with similar data from literature. While formation of pentagon-heptagon pairs at the zigzag graphene edge has been actively investigated in recent years using ab initio methods[25,53,60,61,62,63], we are not aware of such studies for formation of chains at graphene edges. The barriers and energy changes for simultaneous and complete reconstruction of the zigzag edge[53,60,61] as well as formation of the first[25,62,63] and second[62] pentagon-heptagon pairs have been reported.…”

“…Such a difference in the results of the same authors can be explained by insufficiently large supercells used. In Ref 25,. the supercell included only 4 hexagons along the GNR edge.…”

Energetics of atomic scale structure changes in graphene

“…Tensile stress was shown to increase energies of the pristine and defected zigzag edges, decreasing the activation energy for the firststep transformation with 0.21 eV per % rate. 73 Therefore, a uniaxial strain of 5% is sufficient to provoke reconstruction of the zigzag edge at room temperature. 73,77 Fracture of a monolayer graphene was shown to be governed by the competition between bond breaking and bond rotation at a crack tip.…”

“…The energetics of all atomic-scale reactions change upon approaching graphene edges, 52,56,[67][68][69][70][71] and this is especially important for graphene nanoribbons. Edge reconstructions with the formation of topological defects are frequently observed under electron irradiation 13,[72][73][74][75]270 and significantly deteriorate elastic 76 and fracture 77 properties of graphene nanoribbons. Creation of defects at the edges of graphene nanoribbons can also be used to tune electron [78][79][80][81][82][83][84][85] and thermal 86 transport.…”

Giant valley drifts in uniaxially strained monolayerMoS2

“…9 Strain engineering for a long time is used successfully to improve the performance of conventional metal-oxidesemiconductor field-effect transistors. In graphene-based systems strain has revealed interesting effects on the electronic properties [10][11][12][13][14][15][16][17] and also in monolayer MoS 2 it is attracting great attention in recent years. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] One of the most remarkable observations is the fact that strain can be used to transform monolayer MoS 2 from a semiconductor into a metal.…”