Effect of overlayer–substrate interaction on the coalescence behaviors of in-plane graphene/hexagonal boron nitride heterostructures

Abstract

In-plane graphene/hexagonal boron nitride (h-BN) heterostructures show promising applications in novel two-dimensional electronic and optoelectronic devices. The quality of graphene/h-BN (G-BN) domain boundaries, which plays a critical role in device performances, depends on their coalescence. Here, the coalescing mechanism determined by the overlayer–substrate interaction and the growth dynamics during the heterostructure synthesis were studied by in situ surface imaging measurements. In-plane G-BN heterostructures were grown (h-BN first and graphene then) on Pt(111) and Ru(0001) surfaces by chemical vapor deposition. Oxygen intercalation acted as a probe reaction to investigate the coalescing behaviors of the G-BN domain boundaries. Oxygen atoms can intercalate from the outer graphene edges and cross the G-BN domain boundaries into the interior h-BN zone on Pt(111) surfaces. On Ru(0001) surfaces, only interior h-BN domains could be intercalated from G-BN domain boundaries, while no intercalation occurred on outer graphene domains. This shows that graphene can seamlessly stitch with h-BN on Pt(111) but not on Ru(0001), because the weaker overlayer–substrate interaction on Pt(111) compared to that on Ru(0001) makes the G-BN coalescing interface flatter and allows stitching at an identical height. High-quality in-plane G-BN heterostructures are expected to grow on weakly interacting surfaces rather than on strong ones.