Tuning the graphene work function by uniaxial strain

He, Xin; Tang, Ning; Sun, Xiaoxiao; Gan, Lin; Ke, Fen; Wang, Tao; Xu, Fujun; Wang, Xinqiang; Yang, Xuelin; Ge, Weikun; Shen, Bo

doi:10.1063/1.4906995

Cited by 34 publications

(23 citation statements)

References 35 publications

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“…Mechanical periodic structuring of graphene is known to influence its electronic properties via the bending induced strain . Recent KPFM measurements reported a WF increase up to 160 meV at the substrate strain 7%. The graphene strain was actually much lower due to graphene sliding as indicated by the 2D Raman band shift −18.4 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

Doping Effects and Grain Boundaries in Thermal CVD Graphene on Recrystallized Cu Foil

Čermák

Yamada

Ganzerová

et al. 2016

Adv Materials Inter

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Thermal chemical vapor deposition (CVD) of graphene on a copper (Cu) foil is strongly affected by Cu foil recrystallization and grain formation resulting in a heterogeneous graphene layer. Correlated microscopic scanning probe techniques show different chemical and structural properties (Raman microspectroscopy), electrical conductivity (conductive atomic force microscopy), and electronic structure (Kelvin probe force microscopy) across various types of grains. Graphene on clean Cu grains exhibits work function (WF) higher by 300 meV. This is attributed to the contact doping effect. Graphene of higher quality is formed on Cu grains with a surface cuprous oxide (Cu2O) which forms during the thermal CVD process. The graphene WF is higher by 430 meV there. The WF difference is attributed to the contact doping effect and additional strain‐induced doping due to the highly corrugated Cu2O surface. Local electrical conductivity measured by atomic force microscopy and a pair of conductive microprobes corroborates different graphene quality on various Cu grains and reveals that graphene is electrically interrupted at the Cu grain boundaries. Corresponding structural and electronic model of thermal CVD graphene on the Cu foil is presented. The correlation of grain boundaries in Cu foil and graphene is discussed.

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Section: Resultsmentioning

confidence: 99%

Doping Effects and Grain Boundaries in Thermal CVD Graphene on Recrystallized Cu Foil

Čermák

Yamada

Ganzerová

et al. 2016

Adv Materials Inter

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“…The observed red shift in the position of the 2D peak is smaller than the values of 64 cm −1 per % uniaxial strain reported by Mohiuddin et al ., on a mechanically exfoliated single layer graphene flake free of wrinkles and grain boundaries associated with CVD-grown material [9]. In our case, we must therefore presume that the observed relaxation of folds/wrinkles leads to a sliding at the graphene-PET interface [7], and use the single-grain data as a reference to calibrate the effective vs. nominal strain in our measurements. Fig.…”

Section: Scanning Probe and Raman Measurementsmentioning

confidence: 99%

“…The elastically driven deformation of the C-C bonds changes the vibrational and electronic spectra and therefore affects a large number of physical properties of graphene. Uniaxial strain, which is the easiest type of deformation to implement, was experimentally found to influence the electrical resistivity [5,6], the work function [7], Raman peaks [8][9][10], and visible light transmission spectra [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of uniaxial strain on the optical Drude scattering in graphene

et al. 2017

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Graphene is a mechanically robust 2D material promising for flexible optoelectronic applications. However, its electromagnetic properties under strain are experimentally poorly understood. Here we present the far-infrared transmission spectra of largearea chemical-vapor deposited monolayer graphene on a polyethylene terephthalate substrate subjected to uniaxial strain. The effective strain value is calibrated using the Raman spectroscopy and corrected for a relaxation of wrinkles and folds seen directly by atomic-force microscopy. We find that while the Drude weight and the Fermi level remain constant, the scattering rate increases by more than 10% per 1% of applied strain, showing a high level of reproducibility during strain cycling. As a result, the electronic mobility and optical absorption of graphene at terahertz and lower frequencies appear to also be sensitive to strain, which opens pathways to control these key parameters mechanically. We suggest that such a functionality can be potentially used in flexible optoelectronic and microelectromechanical systems based on graphene. By combining our findings with existing theoretical models, we discuss the possible mechanisms of strain-controlled Drude scattering.

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“…[27][28][29][30][31] Since many physical properties (e.g., electrical and optical) depend on the band structure, band structure tuning is of future importance. Even though for graphene and monolayer TMDs, such tuning through the application of strain was investigated extensively both theoretically and experimentally, [14][15][16][17][18][19][20][21][32][33][34][35][36][37] there are only few theoretical studies on strain engineering in heterostructures, [38][39][40] and experimental insight is still yet to be provided.…”

mentioning

confidence: 99%

Strain engineering in monolayer WS2, MoS2, and the WS2/MoS2 heterostructure

Zhu

et al. 2016

Applied Physics Letters

Self Cite

154

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Mechanically exfoliated monolayers of WS2, MoS2 and their van der Waals heterostructure were fabricated on flexible substrate so that uniaxial tensile strain can be applied to the two-dimensional samples. The modification of the band structure under strain was investigated by micro-photoluminescence spectroscopy at room temperature as well as by first-principles calculations. Exciton and trion emissions were observed in both WS2 and the heterostructure at room temperature, and were redshifted by strain, indicating potential for applications in flexible electronics and optoelectronics.

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Tuning the graphene work function by uniaxial strain

Cited by 34 publications

References 35 publications

Doping Effects and Grain Boundaries in Thermal CVD Graphene on Recrystallized Cu Foil

Doping Effects and Grain Boundaries in Thermal CVD Graphene on Recrystallized Cu Foil

Effect of uniaxial strain on the optical Drude scattering in graphene

Strain engineering in monolayer WS2, MoS2, and the WS2/MoS2 heterostructure

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