Abstract
Understanding the chemical and physical mechanisms at play in 2D materials growth is critical for effective process development of methods such as chemical vapour deposition (CVD) as a toolbox for processing more complex nanostructures and 2D materials. We employ a combination of density functional theory and microkinetic modelling to comprehensively investigate the reaction mechanism governing the epitaxial growth of hexagonal boron nitride (hBN) on Ru(0001) from borazine. Our analysis encompasses four key stages prior to the formation of the complete hBN overlayer: (i) adsorption, diffusion and deprotonation of borazine, (ii) dimerisation and microkinetic modelling (iii) stability of larger borazine polymers and (iv) formation of nanoporous intermediates. In doing so, we follow for the first time the exact deprotonation sequence and illustrate its crucial role for the formation of nanostructures. Our findings do not only provide insights into the epitaxial growth of hBN and the stability of intermediate overlayers, which are strongly dependent on surface temperature and the amount of precursor exposures, they offer also crucial guidance for producing high-quality hBN monolayers with regular patterns or functionalisation. Importantly, our results align with experimental data and provide a detailed model which explains temperature-dependent, in-situ surface measurements during hBN growth on Ru.