Growth of the twisted bilayer graphene: Interactions between underlying grains

Che-Men Chu^1*, Wei-Yen Woon¹

¹Department of Physics, National Central University, Taoyuan, Taiwan

* Presenter:Che-Men Chu, email:a1234gy@gmail.com

This work is an investigation of the growth of twisted bilayer graphene through chemical vapor deposition (CVD). The underlying multiple merged adlayer grains of single-crystalline graphene are grown on the copper substrate by utilizing the formed nucleation and growth dynamics involving the carbon source. Through a computational algorithm exploiting Raman characteristics, the distribution of the twist angles is acquired from a tremendous amount of spatial micro-Raman mapping. The statistics present the specific twist angles (3–8°, 8–13°, and 11–15°) formed from the merging adlayer grain though thermodynamically stable configuration should be Bernal stacking and decoupled stacking(>15°). The merging process of bilayer graphene formation with specific angles (termed as TBLG) is investigated through the distribution of the isotope carbon Raman feature. The possibility and areal proportion of TBLG are strongly dependent on the edge configuration of the merging adlayer grains. The carbon source to enlarge graphene is impacted by the approaching grains so that the affected growth rate benefits the occurrence of the TBLG. An extremely high possibility and an areal fraction of TBLG are acquired through the implantation of an extra carbon source. The copper at the implantation region becomes amorphous preventing the adlayer graphene generated, but the convex generated at the edge is advantageous for the formation of nucleation. The implanting and introducing of carbon sources enlarge graphene in the non-implantation region. Consequently, the areal fraction and the possibility of the TBLG reflect the variation of the growth rate and the edge configuration of merging adlayer grains, respectively.

Keywords: graphene, twist angle , bilayer graphene, Raman spectroscopy