Effects of the Substrate Structure on the CVD Growth of Two-Dimensional Hexagonal Boron Nitride

Abstract

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.

Figure-of-Merit in 2D Insulators Pertaining to the Thermokinetics of Hexagonal Boron Nitride via Atmospheric-Pressure Chemical Vapor Deposition (APCVD) on Cu: Origin and Scenario

“…To discover the kinetical growth behaviors of hBN, the contributions of step-edge-terrace Cu structures are inevitable and have been long acknowledged. − Kinetic models of hBN CVD growth proposed on Pd(111) and Ni(111) hinted that step-terrace structures of metallic substrates not only launch a platform for nucleation and growth but also dictate the growth kinetics of hBN to follow either uphill or downhill pathways. , At a minimum, step-edges take charge of the formation of folding or fracture of CVD-grown 2D layers, which is a crucial aspect of mechanics for CVD. At an extreme, such bunching of step-edges gives terraces the opportunity to perform the growth of hBN.…”

“…12 However, the step-guided growth can be thwarted when the chemisorption is kinetically controlled higher on the terrace planes rather than on step-edges, which might pose insurmountable obstacles to the development of CVD hBN. Even though the growth mechanisms were observed and well explained by practical experiments on Pd(111), 13 and computational methods on Ni(111), 14 the growth on Cu(111) was used as a benchmark against, which researchers can measure the kinetic behaviors of hBN because Cu(111) has been widely used as a template for the growth of hBN via CVD. Expanding research on hBN, both in conceptual studies and optimizations, has contributed greatly to our understanding of this material.…”

Growth mechanisms of monolayer hexagonal boron nitride (h-BN) on metal surfaces: theoretical perspectives

“…The impacts of substrate architecture on the CVD development of h-BN have recently been investigated using rMD simulation. 206 A low precursor deposition rate favors large single-domain h-BN growth on normal and vacancy-disordered Ni (111) substrates at high temperature (1500 K), but a greater deposition rate provides a single domain on rough (terrace and step structure) Ni ( 111) surfaces, as shown in Fig. 8c and d.…”

“…However, additional knowledge about the growth process is largely based on investigations of other standard precursors without verication. The general growth strategy for h-BN consists of three phases: 152,153,[204][205][206] (i) precursors (borazane, borazine, etc.) decomposition, (ii) deposition and nucleation of h-BN clusters from the B and N-containing species, and (iii) continual enlargement of h-BN chains from these clusters and attachment to form a large lm.…”

“…For 111) surfaces. 206 single-domain h-BN development, it is also discovered that the initial development rate of h-BN is higher on the rough surface and lower on the vacancy-disordered substrate. On a normal Ni surface, the creation of continuous h-BN islands is larger than on the other two substrates.…”