Improved hBN Single-Crystal Growth by Adding Carbon in the Metal Flux

High-yield growth of large-sized single-crystal hexagonal boron nitride (hBN) bulk is receiving growing research interest due to its graphene-like two-dimensional structure while having distinct electrical and optical properties. In this study, enhanced yield and domain size were realized by adding carbon into the metal flux system (Ni–Cr) under atmospheric pressure. We found that both the yield and domain size increased more than 10 times in optimized carbon amount when compared with metal flux without carbon added. X-ray diffraction, Raman scattering, transmission electron microscope, energy-dispersive X-ray spectroscopy, and electron energy loss spectroscopy results confirmed single-phase hBN without detectable carbon or metal impurity. We suggest that the use of carbon provides a low-cost, stable, and safe alternative to achieve large-sized hBN single crystals.