Strain Assessment in Graphene Through the Raman 2D' Mode

TL;DR

This paper demonstrates that the Raman 2D' mode provides a reliable and doping-insensitive method for local strain assessment in graphene, offering comparable accuracy to traditional methods even under doping conditions.

Contribution

It introduces the use of the Raman 2D' mode as a superior alternative for strain measurement in graphene, especially when doping effects are present.

Findings

2D' mode offers accurate strain assessment similar to G mode.

2D' mode is less affected by doping effects.

Method is effective under various experimental conditions.

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.