Effect of Ni and Cu catalysts on graphene growth under different ethanol flow rates using atmospheric pressure chemical vapor deposition

In this work, a Graphene (Gr) based film was grown on Ni and Cu catalytic substrates by using atmospheric pressure chemical vapor deposition (APCVD) technique at various ethanol flow rates. The Cu and Ni catalytic substrates were placed together in the reaction chamber to ensure similar growth conditions. The Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, energy dispersive x-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM) techniques were used to investigate the structural, optical and morphological properties of the APCVD grown grapheme layer. The crystallite size (L-a), defect density (n(D)), distance between point defects (L-D) and the graphene thickness were estimated. The values of L-a and L-D were found to be higher in the case of Gr/Ni as compared to the Gr/Cu, indicating the better crystalline quality of the Gr/Ni layer. The increasing trend for the graphene thickness against ethanol flow rates was observed for Gr/Cu and Gr/Ni samples. The Raman spectroscopic results and the light transmittance revealed that the Ni substrate promotes the formation of a multilayered Gr whereas the Cu has the advantage of producing mono to few-layered graphene films. The Gr/Ni samples exhibited low defects level which completely disappeared in the sample which was deposited at 30 sccm ethanol/H-2 flow rate. The significant difference in defects/disorder level between Gr/Ni and Gr/Cu was attributed to a different in their growth mechanisms.