Low-Temperature Synthesis of Large-Area Hexagonal Boron Nitride Films on Diverse Substrates by Plasma Afterglow Deposition

Hexagonal boron nitride (hBN) is a van der Waals material with excellent insulating properties that make it well-suited as a gate dielectric in 2D electronic devices. In recent years, the discovery of an ever-increasing list of properties has led to a much broader range of potential applications, including quantum photonics, memristive devices, and extreme-environment coatings. However, current growth methods for hBN films are characterized by a narrow selection of substrates and high temperatures that require transfer and limit scale-up. Here, we report a remote plasma-activated approach to directly synthesize large-area hBN films on a diverse range of representative metallic, semiconducting, and amorphous insulating substrates. Specifically, we employ the spatial afterglow of an Ar/H2 plasma to activate ammonia borane, which enables the growth of thick (>30 nm), uniform, and stoichiometric films on substrates such as Si, SiO2, glass, fused silica, Mo, and Al. Systematic spectroscopic characterization reveals that hBN films can be grown as low as 300 °C. Furthermore, plasma afterglow-grown hBN films exhibit mechanical, electrical, and thermal properties on par with or exceeding those reported by alternate synthesis methods. These results establish plasma afterglow growth for the direct integration of hBN into a wide range of emerging technologies.