Large-Scale Growth of High-Quality Hexagonal Boron Nitride Crystals at Atmospheric Pressure from an Fe-Cr Flux

Single crystals of hexagonal boron nitride (hBN) have recently been envisioned for electronic, optoelectronic, and nanophotonic applications. In this study, the production of large-scale, high-quality hBN single crystals via precipitation from a new solvent composed of Fe and Cr was demonstrated to be viable at atmospheric pressure. The clear and colorless crystals have a maximum domain size of around 2 mm and a thickness of around 200 μm. The Raman spectra and photoluminescence emission spectra demonstrate that the crystals produced with this solvent are pure hBN phase, and with low defect and residual impurity concentrations. The use of an Fe-Cr mixture provides a lower cost alternative to the more common Ni-Cr solvent for growing large hBN of comparable quality.