Raman spectroscopy is a widely used technique for the analysis of graphene materials within single academic and industry contexts. This technique is characterized by its ease of implementation, rapidity, and non-destructive nature. Spectra resulting from this technique typically consist of two bands (G and 2D), which gives the spectra a seemingly simple appearance. Indeed, as early as 2007, Raman criteria were proposed to determine the number of layers in a stack based solely on the Raman spectrum. However, a multitude of studies published since 2007 have demonstrated that behind this apparent simplicity lie multiple effects that affect the G and 2D bands, thereby rendering interpretation complex and the determination of the number of layers in a stack uncertain. Furthermore, Raman spectroscopy has emerged as a pivotal technique for the analysis of twisted structures and diverse stacking sequences, such as ABA and ABC, which have culminated in significant discoveries, including strongly correlated states such as unconventional superconductivity. In addition to the resonance effects associated with superlattice formation, the shape of the 2D band provides valuable insight into stacking types, although its interpretation remains complex. In this article, we propose a methodology for interpreting the 2D Raman band that is informed by a review of selected references of the extant literature as well as original data. A compendium of recommendations and a series of diagrams are also provided to address other physical effects that can complicate spectral interpretation.
Dinar et al. (Tue,) studied this question.