Understanding the Electronic Structures for Different Stacking Modes Bilayer CVD Graphene through Chemical Modification

Abstracts

Different electronic structures between two identical Chemical Vapor Deposition (CVD) growth stacking modes bilayer graphene (BLG) which are known as AB stacking (Bernal-stacked) and twisted (non-AB stacking or turbostratic-stacked) graphene, are firstly performed by chemical functionalization with diazonium salts. The chemical modification results of two stacking modes graphene with aromatic diazonium ions are analyzed by Raman Spectroscopy. By calculating the I_D/I_G ratio from Raman spectrum, we find the grafting speed for AB stacking bilayer graphene is much lower than for twisted graphene. We attribute the difference of reaction rates between two stacking modes to the difference of resonance force and the density of states (DOS) between the upper layer and the under layer in this two modes. After D band Raman mapping, the areas of two stacking modes have a significant different shown up rate. Also we find that this reaction speed difference has an edge and bulk area dependence in both two modes BLG. Further TEM, SAED, and XPS test confirm the two stacking modes and the reaction of grafting. This chemical modification by introducing a sp³ defect provides a visible and new way for observing and understanding the DOS and different physical structures between two stacking modes CVD BLG.