(201ag) All CVD Direct Growth of Large-Scale Graphene and Hexagonal Boron Nitride Heterostructures

Transfer-free and direct growth of large-scale graphene/hexagonal boron nitride (h-BN) heterostructures will be an important advancement in the development of high performance nano and optoelectronic devices. Atomically flat surface and lack of charged impurities enable h-BN an ideal substrate platform for complex 2D heterostructured circuits. However, current techniques mostly rely on the transfer (mechanical or chemical) of both h-BN and graphene to build the 2D heterostructures, which ultimately degrade their structure and properties, implying underperformance of the final devices. Here we report the direct growth of large-scale graphene/h-BN heterostructures via chemical vapor deposition (CVD). First, h-BN is directly synthesized on SiO₂/Si substrates via chemical-interaction guided mechanism followed by the deposition of a thin metal film (Cu) on h-BN/SiO₂/Si substrates. Then graphene is grown via a process, which relies on the diffusion of catalytically produced carbon radicals through Cu grain-boundaries and their crystallization at the interface of Cu and h-BN/SiO₂/Si dielectrics. Finally, removing the top graphene and Cu, produces the graphene/h-BN heterostructures with a sharp defect-free interface. The directly-grown, van der Waals bound graphene/h-BN heterostructures are characterized by scanning Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Futuristically, this all-CVD direct growth strategy will be a transformative approach for scalable production of complex 2D van der Waals heterostructures.