Single process CVD growth of hBN/Graphene heterostructures on copper thin films

In this study, we have successfully grown hBN/graphene heterostructures on copper thin films using chemical vapor deposition in a single process. The first and most surprising result is that graphene grows underneath hBN and adjacent to the Cu film even though it is deposited second. This was determined from cross-sectional TEM analysis and XPS depth profiling, which chemically identified the relative positions of hBN and graphene. The effect of various growth conditions on graphene/hBN heterostructures was also studied. It was found that a pressure of 200 torr and a hydrogen flow rate of 200 sccm (similar to 1 H-2/N-2) yielded the highest quality of graphene, with full surface coverage occurring after a growth time of 120 min. The resulting graphene films were found to be approximately 6-8 layers thick. The grain size of the nanocrystalline graphene was found to be 15-50 nm varying based on growth conditions.