Hexagonal boron nitride (h-BN) has received a great deal of attention as a substrate material for high-performance graphene electronics because it has an atomically smooth surface, lattice constant similar to that of graphene, large optical phonon modes, and a large electrical band gap. Herein, we report the largescale synthesis of high-quality h-BN nanosheets in a chemical vapor deposition (CVD) process by controlling the surface morphologies of the copper (Cu) catalysts. It was found that morphology control of the Cu foil is much critical for the formation of the pure h-BN nanosheets as well as the improvement of their crystallinity. For the first time, we demonstrate the performance enhancement of CVDbased graphene devices with large-scale h-BN nanosheets. The mobility of the graphene device on the h-BN nanosheets was increased 3 times compared to that without the h-BN nanosheets. The on−off ratio of the drain current is 2 times higher than that of the graphene device without h-BN. This work suggests that high-quality h-BN nanosheets based on CVD are very promising for high-performance large-area graphene electronics.
Because of the low solubility of N atoms in metals, hexagonal boron nitride (h-BN) growth has explained by surface reaction on metal rather than by penetration/precipitation of B and N atoms in metal. Here, we present an impressive pathway of h-BN formation at the interface between Ni and oxide substrate based on B-N molecular diffusion into Ni through individual atomic vacancies. First-principles calculations confirmed the formation energies of the h-BN layers on and under the metal and the probability of B-N molecular diffusion in metal. The interface growth behavior depends on the species of metal catalysts, and these simulation results well support experimental results.
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