Role of limited hydrogen and flow interval on the growth of single crystal to continuous graphene by low-pressure chemical vapor deposition

A method for defect-free large crystallite graphene growth. remains unknown despite much. research effort. In this work, we. discuss the role of flow duration of H-2 gas for the production of graphene as per requirement and production. at a minimum flow rate considering the safety issue of hydrogen utilization. The copper substrate used for growth was treated for different time intervals (0 to 35 min) in H-2 flow prior to growth. Structural and chemical changes occurring. in the copper substrate surface were. probed by grazing incidence. x-ray diffraction and x-ray photoelectron spectroscopy. The results were correlated with the Raman spectroscopy data, which can quantify the quality of graphene. With increasing. H-2 flow interval, secondary nucleation sites were observed and growth favored. few-layer graphene structures. The surface-adsorbed oxygen molecules and its conversion to an. OH terminated surface. with increasing hydrogen flow interval was found to be a key factor in. enhancing nucleation density. The Stranski-Krastanov type of nucleation was observed for samples grown with different time intervals of H-2 treatment, except 5 min of H-2 flow prior to growth for which the Volmer-Weber type of growth favored. monolayer graphene crystallite growth