Effects of H2 annealing on polycrystalline copper substrates for graphene growth during low pressure chemical vapor deposition

• Copper crystallographic orientations changed as a result of hydrogen annealing.
• Graphene films were grown on the copper foils under hydrogen annealing.
• No graphene Raman signals were observed on copper foils without hydrogen annealing.
• Hydrogen/methane ratio played an important role in CVD graphene deposition process.

It has been shown that the hydrogen annealing process plays an important role on the crystallographic orientation changes of polycrystalline copper substrates during low pressure chemical vapor deposition (LPCVD) of graphene, which subsequently influence the generation of graphene films. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the copper foil crystallographic orientation and morphology changes with and without hydrogen annealing. Graphene films were successfully synthesized on copper foils by LPCVD at 1000 °C with hydrogen annealing process. Raman spectroscopy was also performed to determine the formation of graphene films as well as their quality. Without hydrogen annealing no significant graphene Raman signal are detected and it is hypothesized that this is related to the different crystallographic orientations of copper substrates.