Nucleation Mechanism of Hexagonal Boron Nitride on Diamond (111) and Its Hydrogen-Terminated Surface: A DFT Study.

Hexagonal boron nitride (h-BN) has attracted significant attention due to its exceptional properties. Among various substrates used for h-BN growth, diamond emerges as a more promising substrate due to its high-temperature resistance and superior electrical properties. To reveal the nucleation mechanism of h-BN on the diamond (111) surface and the impact of hydrogenation treatment on this process, we explored the adsorption, diffusion, nucleation morphologies, and predicted nucleation pathways in this process using first-principles calculations based on density functional theory (DFT). Our results indicate that N positioned above the first layer of C and B positioned above the second layer of C enhance the stability of BN clusters. During the growth of BN clusters, there is a geometric transformation from chain-like structures to honeycomb-like structures. The proportion of unhybridized sp atoms within BN clusters and geometric symmetry significantly influence h-BN growth. Moreover, computational findings also suggest that to enhance the nucleation rate of h-BN it is essential to inhibit the formation of zigzag chain structures by BN clusters during the early stages of nucleation on a clean diamond surface. Additionally, hydrogenation treatment decreases the binding affinity of B and N on the substrate, facilitating atomic diffusion, and has been identified as an effective approach to facilitate nucleation. Furthermore, hydrogen-terminated diamond acts as an electron donor in the system, which profoundly affects the morphology of growing h-BN and the characteristics of the h-BN/diamond heterostructures. These conclusions are important to understanding and optimizing h-BN growth on diamond and provide a theoretical basis of the construction and application of the h-BN/diamond heterostructure.