Influence of growth kinetics on graphene domains shape under atmospheric pressure chemical vapor deposition

In this work, the role of gas kinetics in the growth of lobed graphene domains by atmospheric pressure chemical vapor deposition (AP-CVD) is elucidated by sandwiching Cu foil between Si/SiO2 wafers. Two different growths were carried out: (1) A Cu foil was placed at the center of a quartz tube in AP-CVD for graphene growth and (2) another Cu foil was sandwiched between Si/SiO2 wafers to alter the nucleation growth kinetics of graphene domains to mimic those in low-pressure chemical vapor deposition (LP-CVD). From the scanning electron microscopy (SEM) images, the graphene domains of the sandwiched Cu foil displayed mostly four-lobed, parallel-sided domains which are usually obtained under LP-CVD as compared to Cu foil without sandwiching which showed typical hexagonal graphene domains of AP-CVD. The Raman spectroscopy confirmed that the domains are single-layer graphene. An electron backscatter diffraction (EBSD) showed that the Cu foil is predominantly (001). The results of this study agree with the theoretical predictions of growth kinetics in graphene synthesis by CVD and showed that it is possible to obtain single-layer graphene domains which are usually obtained under LP-CVD by restricting the gas flux through the boundary layer. Graphic abstract