Strain Assessment in Graphene Through the Raman 2D′ Mode

Abstract

Accurate and simple local strain assessment in graphene is one of the crucial tasks in device characterization. Raman spectroscopy is often used for that purpose through monitoring of the G and 2D modes. However, the shifts of those two bands might be biased, especially under uniaxial strain, by the effects of charge-transfer doping. Therefore, it is extremely desirable to use another Raman band, less affected by doping, but with a defined and measurable behavior under strain.The Raman 2D' mode is in this sense the ideal feature for the evaluation of strain levels in stretched graphene monolayers, suitable for this task even under different experimental conditions. The sensitivity and accuracy of the approach through 2D' mode is on the same level as through the G mode, however, the clear advantage of the 2D' arises when doping effects are present in the sample.On top of that, since the value the 2D' splitting is used for the strain level quantification, and not the shift rates of the components, the doping effects should not influence this value even if present. The close proximity of our value, incl. a small 95% confidence interval, to the one predicted in 38 points to the viability of both the presented experimental and previous theoretical 38 results. AUTHOR INFORMATION

Stress and charge transfer in uniaxially strained CVD graphene

“… a The real strain, calculated by multiplying the stress transfer efficiency and the maximum achieved nominal strain ϵ m .…”

Feasibility of polyethylene film as both supporting material for transfer and target substrate for flexible strain sensor of CVD graphene grown on Cu foil

“…Previous reports have demonstrated that such Raman peak shis are associated with deection, strain, or doping. [41][42][43] In our experiment, strain might be induced when graphene was transferred onto PE lm, which would result in an upshi of the 2D peak.…”

Nanostructures in suspended mono- and bilayer epitaxial graphene

“…-We have seen this splitting also in the width increase of the 2D' peak around a graphene nanoconstriction (fig S11) and this peak is said to be much less sensitive to doping effect 27 than the G peak.…”

“…Due to the 2D nature of graphene, the thermal transport and phonon behavior is neither diffusive nor ballistic 25 and thermal conductivity unexpectedly depends on the sample size 26 . As a consequence, the geometry of the devices strongly affects the thermal conduction behavior which is still under debate [25][26][27] . In order to connect the porosity of our nanostructures and their thermal conductivity, we have also studied the Raman peak behavior of our devices under laser heating, at different powers (see Figure 3).…”