Due to its outstanding stability, flat surface, and wide band gap, twodimensional hexagonal boron nitride (h-BN) has appeared as a vital element in a range of applications, including a perfect substrate for graphene devices, tunneling barriers, and deepultraviolet emitters. However, large-scale growth of high-grade h-BN using chemical vapor deposition (CVD) still remains challenging due to its dependence on a variety of parameters such as substrate structures, temperature, and precursor deposition rates. Here, we explore the atomic scale elementary nucleation and growth process of monolayer h-BN on normal, vacancy-disordered, and rough (terrace and step structure) Ni(111) surfaces using reactive force field molecular dynamics simulations. The impact of the precursor deposition rate and temperature on different Ni(111) substrates was also investigated. At 1500 K, a low precursor deposition rate favors large single-domain h-BN development on normal and vacancy-disordered Ni(111) substrates, whereas a higher deposition rate yields a single domain on a rough substrate. It is also explored that the initial growth rate of h-BN is higher on the rough substrate and lower on the vacancy-disordered substrate for single-domain h-BN growth. The formation of continuous h-BN islands is greater on a normal Ni substrate than the other two substrates. Although a small vacancy concentration (1.25%) in the Ni(111) substrate shows a minor effect on the growth of the h-BN layer, the rough surface shows a considerable effect on the h-BN growth. These findings pave the way for scalable high-quality CVD growth of h-BN, taking this promising material one step closer to practical applications.
Two-dimensional hexagonal boron nitride (h-BN) has appeared as a promising material in diverse areas of applications, including as an excellent substrate for graphene devices, deep-ultraviolet emitters, and tunneling barriers, thanks...
Chemical vapor deposition (CVD) through sulfidation of MoO3 is one of the most important synthesis techniques to obtain large-scale and high-quality two-dimensional (2D) MoS2. Recently, H2S precursor is being used in the CVD technique to synthesize 2D MoS2. Although several studies have been carried out to examine the mechanism of MoS2 growth in the presence of sulfur and MoO3 precursors, the growth of MoS2 in the presence of H2S precursor has largely remained unknown. In this study, we present a Reactive molecular dynamics (RMD) simulation to investigate the reaction mechanism of MoS2 from MoO3 and H2S precursors. The intermediate molecules formation, the reason behind those formations, and the surface compositions of MoOxSyHz during the initial steps of CVD have all been quantified. Surprisingly, a sudden separation of sulfur atoms from the surface was observed in the H2S precursor system due to the substantial oxygen evolution after 1660 K. The sulfur detachments and oxygen evolution from the surface were found to have a linear relationship. In addition, the intermediate molecules and surface bonds of MoS2 synthesized by MoO3 and H2S precursors were compared to those of a system using S2 and MoO3 precursors. The most stable subsidiary formation from the H2S precursor was found to be H2O, whereas in case of S2 precursor it was SO. These results provide a valuable insight in the formation of large-scale and high-quality 2D MoS2 by the CVD technique.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.