Raman spectroscopy on few layer graphene

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MS; 2023; Centre for nano science and engineering

Graphene is a two-dimensional allotrope of carbon exhibiting planer honeycomb lattice structure.1 A carbon atom in graphene makes three σ-bonds with the neighbouring atoms in the plane and one π-bond perpendicular to the plane of these carbon atoms. The delocalized electron due to side overlapping of π-bond in graphene gives high intrinsic carrier mobility. The maximum carrier mobility of single layer suspended graphene is 200,000 cm2V-1s-1,2 whereas the maximum carrier mobility of silicon is 1,400 cm2V -1s-1. 3 Hence, graphene is an excellent substitute for high-frequency FET switch over silicon FET switch. The three σ-bonds (tight bonds) make graphene the strongest material among all other materials. The free-standing singlelayer graphene shows Young's modulus as high as 1TPa, while that of carbon nanotube is reported to be around 270-950 GPa. 4 This implies that graphene can be a promising material for nanoelectromechanical systems (NEMS). The distinct electronic and mechanical properties of graphene have attracted a lot of attention for developing alternative graphene-based alternative, which helps address the technical limits of current technologies. Few layers graphene (FLG) have been studied both theoretical and experimentally.6,7 These studies show that the number of layers and staking orders of FLG has a strong influence on its characteristic properties. Hence, identifying the structural differences in FLG is a crucial requirement in developing FLG-based devices. The characteristic properties of monolayer and bilayer graphene have been extensively studied. However, there are very few reports on three or more-layers of graphene. Here, we have focused on identifying and fabricating few layers graphene (FLG) devices and studying their electrical and optical characteristics.