Si trova su / Altri legami
© 2021 Author(s).Hexagonal boron nitride (h–BN) is a critical 2D insulator used as a substrate, gate dielectric, or encapsulation layer for graphene and other 2D materials and their van der Waals heterostructures. It is also promising as an active layer in single–photon emitters and other photonic devices. With the chemical formula H3N–BH3, ammonia borane is the most attractive precursor for up–scalable growth of large–area h–BN, using chemical vapor deposition given its stoichiometric B:N ratio, high stability under ambient conditions, nontoxicity, and high solubility in common solvents. Here, the synthesis of large–area (100 × 150 mm2) crystalline hexagonal boron nitride layers by thermal activation and decomposition of the precursor ammonia borane is presented. We describe two different reaction pathways for h–BN synthesis, providing evidence for dissimilarities in the sublimation kinetics of ammonia borane and how these differences critically influence the growth of h–BN. This understanding helps us accelerate h–BN production, reuse precursors, and reduce machine runtime, paving the way for upscalability. Moreover, our work provides a consistent unified view explaining the diverse deposition conditions reported in the literature for h–BN grown by CVD using ammonia borane as a precursor.
