Raman Spectroscopy-Based Techniques for 2D Layered Materials

Abstract

It is important to identify the number of layers /thickness present in 2D materials. The techniques such as atomic force microscopy, optical contrast, and Raman spectroscopy have widely been used to determine the number of layers of 2D materials. Among all of them, Raman spectroscopy is a very much rapid, non-destructive, and direct apparatus to identify the number of layers /thickness of 2D Materials. Further, the Raman Spectroscopy is a non-destructive chemical analysis technique which provides detailed information about chemical structure, phase and polymorph, crystallinity and molecular interactions. It is based upon the interaction of light with the chemical bonds within a material. It is known that, the two-dimensional materials with remarkably electronic, optical, and mechanical properties, exhibit both high scientific interest and huge application potential. Raman spectroscopy has been proven to be a rapid, suitable and non-destructive technique to characterize the properties of wide range of 2D materials at research laboratory and mass-production scales. In this chapter, we discuss recent advances in application of Raman spectroscopy to 2D materials for probing their fundamental properties. First, we will introduce Raman characterization on different types of 2D Materials, phase transition triggered by defect, electrostatic doping and temperature, thickness-dependent interlayer and interlayer modes, and two-dimensional alloys with tunable compositions. Further, the layer dependent, temperature and pressure dependence Raman spectroscopy of wide range of 2D materials will be analyzed and discussed. The extensive capabilities of Raman spectroscopy in probing quantum phase transition will also be discussed, such as charge density wave and magnetic transition. Then, we will discuss the application of Raman spectroscopy to probe the moiré phonons, interfacial coupling and cross-dimensional electron-phonon coupling in van der Waals heterostructures. Finally, SERS in 2D materials will be discussed. The 2D materials decorated with metallic nanoparticles, the hybrid SERS substrate can provide SERS EF due to the synergic effect of EM and chemical enhancement. The 2D materials, like graphene, MoS2, WS2, WSe2 etc could offer chemically inert and biocompatible surface which is favourable in bio detection.