Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO<sub>2</sub>

Teague, M. L.; Lai, Andrew P.; Velasco, Jairo; Hughes, C. R.; Beyer, André; Bockrath, Marc; Lau, Chun Ning; Yeh, N.-C.

doi:10.1021/nl9005657

Cited by 139 publications

(128 citation statements)

References 30 publications

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“…The ability to monitor and control strain in graphene could be crucial during device fabrication, as it affects the electronic properties of the material itself [97]. For example, it has been recently shown that modulation in electrical [98] and optical [99] conductance can be induced by strain. It has been suggested that by properly modulating strain locally in graphene may lead to a controlled tuning of the electronic band gap [100].…”

Section: Discussionmentioning

confidence: 99%

Probing mechanical properties of graphene with Raman spectroscopy

2010

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The use of Raman scattering techniques to study the mechanical properties of graphene films is reviewed here. The determination of Grüneisen parameters of suspended graphene sheets under uni-and bi-axial strain is discussed, and the values are compared to theoretical predictions. The effects of the graphene-substrate interaction on strain and to the temperature evolution of the graphene Raman spectra are discussed. Finally, the relation between mechanical and thermal properties is presented along with the characterization of thermal properties of graphene with Raman spectroscopy.

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Section: Discussionmentioning

confidence: 99%

Probing mechanical properties of graphene with Raman spectroscopy

2010

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“…The tension can be generated either by the electrostatic force of the underlying gate [20,21], by interaction of graphene with the side walls [22], or as a result of thermal expansion [23,24]. Our main results are as follows.…”

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confidence: 93%

Singular elastic strains and magnetoconductance of suspended graphene

et al. 2010

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Graphene membranes suspended off electric contacts or other rigid supports are prone to elastic strain, which is concentrated at the edges and corners of the samples. Such a strain leads to an algebraically varying effective magnetic field that can reach a few Tesla in sub-micron wide flakes. In the quantum Hall regime the interplay of the effective and the physical magnetic fields causes backscattering of the chiral edge channels, which can destroy the quantized conductance plateaus.PACS numbers: 73.61. Wp, 73.43.Cd, 73.23.Ad The isolation of graphene monolayers [1,2] and the observation of the integer quantum Hall effect (QHE) in these systems [3,4] have made graphene a very active research topic [5,6]. The integer QHE in graphene is remarkably robust and can be seen even at room temperature [7]. The traditional setup to measure the quantized Hall plateaus involves at least four contacts: source and drain for the current, and two (or more) side contacts for the voltage. This scheme helps to eliminate the spurious contact resistance. The much higher mobility of suspended samples [8-10] raised hopes for observing also the fractional QHE in graphene. Yet demonstrating even the integer QHE in a four-contact setup proved to be difficult in such samples. Only recently the integer QHE has been confirmed in suspended graphene [9,11,12] by reverting to a two-contact scheme. (Similar observations have been made for bilayers [13].) The fractional QHE has also been reported in these experiments [11,12]. An artifact of the two-contact setup is the suppression of the quantized conductance [11,12], familiar from the QHE in semiconductors [14][15][16][17]. The reason why the nominally superior multi-contact scheme is less successful in suspended graphene has not been fully clarified, except for one theory that in small samples the side contacts had to be placed too close to the source and drain, causing admixture of the longitudinal and Hall conductances [11].In this paper we consider a different effect, which may also contribute to the lack of quantization: when the graphene sheet is under tension, the side contacts induce a long-range elastic deformation which acts as a pseudomagnetic field B(x, y) for its massless charge carriers [5,18,19]. The tension can be generated either by the electrostatic force of the underlying gate [20,21], by interaction of graphene with the side walls [22], or as a result of thermal expansion [23,24]. Our main results are as follows. We show that B is concentrated near the corners of the contacts where it exhibits power-law singularities. It decays into the interior of the sample but for a reasonable 0.1% average strain in a 200-nm wide strip, B can remain of the order of a Tesla across its entire width. This leads to backscattering of the QHE edge states when the real magnetic field B is in a similar range, causing the erosion of the quantized conductance plateaus. We give an analytical argument that predicts that the QHE plateaus are destroyed above a threshold Landau level index N c and t...

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“…15 Furthermore, it has been shown experimentally that graphene's electronic properties can be modified by application of an electric field 16 or mechanical strain. [17][18][19] Current applications of graphene include field-effect transistors (FETs), 20 impermeable membranes used to trap gases, 21 ultrafast photodetectors, 22 and nanomechanical resonators. 23 Besides these exceptional electronic properties, however, graphene cannot intrinsically exhibit piezoelectric properties because it belongs to a centrosymmetric point group (6/mmm or D 6h ).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Hydrogen and Fluorine Coadsorption on the Piezoelectric Properties of Graphene

2013

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ABSTRACT:Motivated by a search for electromechanical coupling in monolayer materials, we study graphene chemically modified by hydrogen adsorbed on one side and fluorine adsorbed on the other side. Such adsorption under experimental conditions can potentially lead to a variety of configurations of atoms on the surface. We perform an exhaustive evaluation of candidate configurations for two stoichiometries, C 2 HF and C 4 HF, and examine their electromechanical properties using density functional theory. While all configurations exhibit an e 31 piezoelectric effect, the lowest energy configuration additionally exhibits an e 11 effect. Therefore, both e 31 and e 11 piezoelectricity can potentially be engineered into nonpiezoelectric monolayer graphene, providing an avenue for monolithic integration of electronic and electromechanical devices in graphene monolayers for resonators, sensors, and nanoelectromechanical systems (NEMS).

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Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO₂

Cited by 139 publications

References 30 publications

Probing mechanical properties of graphene with Raman spectroscopy

Probing mechanical properties of graphene with Raman spectroscopy

Singular elastic strains and magnetoconductance of suspended graphene

The Effect of Hydrogen and Fluorine Coadsorption on the Piezoelectric Properties of Graphene

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Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO2

Cited by 139 publications

References 30 publications

Probing mechanical properties of graphene with Raman spectroscopy

Probing mechanical properties of graphene with Raman spectroscopy

Singular elastic strains and magnetoconductance of suspended graphene

The Effect of Hydrogen and Fluorine Coadsorption on the Piezoelectric Properties of Graphene

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Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO₂