An easy approach to reveal the metallic nature of graphene by Breit–Wigner–Fano lineshapes using Raman spectroscopy. (15th September 2017)

• Record Type: Journal Article
• Authors: Zafar, Zainab; Zafar, Amina; Tian, Yong; Cao, Zhimin; Jin, Biaobing; Shi, Zhixiang
• Is Part Of: Journal of Raman spectroscopy. Volume 48:Number 10(2017)
• Page Start: 1318
• Page End: 1322
• Publication Date: 2017-09-15
• Subjects: graphene -- metal deposition -- electron–phonon coupling -- Fano resonance -- Breit–Wigner–Fano lineshapes; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.5239
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : Electron–phonon coupling enhancement in metal‐doped single‐layer graphene has been investigated. Different metal adatoms were deposited on chemical vapor deposition (CVD) graphene and annealed at high temperature under vacuum. The interaction between these metals and graphene was studied by Raman spectroscopy. A significant variation in peak width has been observed as a function of annealing temperature. This broadening of the Raman features is understood as a consequence of the coupling of phonon with electron–phonon pairs, and its strength depends on the particular metal deposited. A typical softening and broadening of G peak in Raman spectrum is interpreted as Fano resonance, which is an interaction between a phonon and continuum. This asymmetry in G peak is further analyzed and fitted with Breit–Wigner–Fano lineshapes in terms of asymmetric factor (1/ q BWF ) for different metal‐doped samples as a function of annealing temperature. Hence we demonstrated an easy approach to study the transition from semi‐metallic to metallic nature of graphene. This study may extend the interest in electron–phonon coupling as it aims to manipulate the electronic and magnetic properties of graphene and other 2D systems. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : This work aims to report the detailed investigation of the asymmetry lineshapes in Raman spectra due to metal doping. By systematically focus on the asymmetry region, we have established that this asymmetric linewidth broadening is due to the Fano interaction of continuum with discrete phonon mode. In addition, using BWF lineshapes, which are considered as the 'hallmark' of metallic nature of SWCNT, a simple methodology is proposed to unveil the metallic nature of graphene.