Synthesis of wafer-scale hexagonal boron nitride monolayers free of aminoborane nanoparticles by chemical vapor deposition

Hexagonal boron nitride (h-BN) has gained great attention as a two-dimensional material, along with graphene. In this work, high-quality h-BN monolayers were grown in wafer scale (7 × 7 cm²) on Cu substrates by using low-pressure chemical vapor deposition (LPCVD). We created h-BN monolayers that were free of polymeric aminoborane (BH₂NH ₂) nanoparticles, which are undesirable by-products of the ammonia borane precursor, by employing a simple filtering system in the CVD process. The optical band gap of 6.06 eV and sharp and symmetric Raman peak measured at 1371 cm^-1 indicate the synthesis of monolayer h-BN. In addition, spherical aberration (C_S)-corrected high-resolution transmission electron microscopic images confirm the production of a single-layer hexagonal array of boron and nitrogen atoms.