Growth Dynamics of Millimeter‐Sized Single‐Crystal Hexagonal Boron Nitride Monolayers on Secondary Recrystallized Ni (100) Substrates

The outstanding physical properties of 2D materials have sparked continuous research interest in exploiting these materials for next-generation high-performance electronic and photonic technology. Scalable synthesis of high-quality large-area 2D hexagonal boron nitride (h-BN) is a crucial step toward the ultimate success of many of these applications. In this work, a synthetic approach in which secondary recrystallized Ni (100) substrates underwent a carburization process, followed by the growth of h-BN in a molecular beam epitaxy system is designed. The h-BN growth dynamics is studied by tuning different growth parameters including the substrate temperature, and the boron and nitrogen source flux ratio. With assistance from density functional theory calculations, the role of interstitial C atoms in promoting h-BN growth by enhancing the catalytic effect of the transition metal, which lowers the nucleation activation energy barrier, is rationalized. Through the control of the growth parameters, a single-crystal h-BN monolayer domain as large as 1.4 mm in edge length is achieved. In addition, a high-quality, continuous, large-area h-BN single-layer film with a breakdown electric field of 9.75 MV cm(-1) is demonstrated. The high value of the breakdown electric field suggests that single-layer h-BN has extraordinary dielectric strength for high-performance 2D electronics applications.