Low-Temperature Direct Synthesis of Multilayered h-BN without Catalysts by Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition

Low-temperature direct synthesis of thick multilayered hexagonal-boron nitride (h-BN) on semiconducting and insulating substrates is required to produce high-performance electronic devices based on two-dimensional (2D) materials. In this study, multilayered h-BN with a thickness exceeding 5 nm was directly synthesized on quartz and Si at low temperatures, between 400 and 500 °C, by inductively coupled plasma-enhanced chemical vapor deposition using borazine as the precursor material. The quality and thickness of the h-BN crystals were investigated with respect to synthesis parameters, namely, temperature, radio frequency power, N2 flow rate, and H2 flow rate. Introducing N2 and H2 carrier gases critically affected the deposition rate, and increasing the carrier gas flow rate enhanced the h-BN crystal quality. The typical optical band gap of synthesized h-BN was approximately 5.8 eV, consistent with that of previous studies. The full width at half-maximum of the h-BN Raman peak was 32-33 cm-1, comparable to that of commercially available multilayered h-BN on Cu foil. These results are expected to facilitate the development of 2D materials for electronics applications.