Reactivity of adducts relevant to the deposition of hexagonal BN from first-principles calculations

First-principles calculations, which also implement the nudged elastic band (NEB) code, are performed to investigate (i) the stability of the (C2H5)3B:NH3 adduct formed by the initial precursor molecules triethylborane (C2H5)3B and ammonia NH3 in the metal–chemical-vapor-deposition (MOCVD) of hexagonal BN, and (ii) the energy barrier to the first ethane elimination through consistent unimolecular, ammonia-assisted, and adduct-assisted reaction pathways. Comparison is done with the reference case of the (CH3)3Al:NH3 adduct, notoriously known for its high degree of stability and reactivity, which determines an overall severe parasitic gas-phase chemical reaction mechanism in the deposition of AlN.