title: Growth Mechanism and Morphology of Hexagonal Boron Nitride.
abstract: Hexagonal boron nitride (h-BN) sheet is a structural analogue of graphene, yet its growth mechanism has been rarely studied, as complicated by its binary composition. Here, we reveal an atomistic growth mechanism for the h-BN islands by combining crystal growth theory with comprehensive first-principles calculations. The island shapes preferred by edge equilibrium are found to be inconsistent with experimental facts, which is in contrast to previous common views. Then the growth kinetics is explored by analyzing the diffusion and docking of boron and nitrogen atoms at the edges in a step-by-step manner of the nanoreactor approach. The determined sequence of atom-by-atom accretion reveals a strong kinetic anisotropy of growth. Depending on the chemical potential of constituent elements, it yields the h-BN shapes as equilateral triangles or hexagons, explaining a number of experimental observations and opening a way for the synthesis of quality h-BN with controlled morphology. The richer growth kinetics of h-BN compared to graphene is further extendable to other binary two-dimensional materials, notably metal dichalcogenides.
authors.affiliation: Department of Materials Science and NanoEngineering and Department of Chemistry, Rice University , Houston, Texas 77005, United States.
authors.forename: Zhuhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and NanoEngineering and Department of Chemistry, Rice University , Houston, Texas 77005, United States.
authors.forename: Yuanyue
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Materials Science and NanoEngineering and Department of Chemistry, Rice University , Houston, Texas 77005, United States.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Materials Science and NanoEngineering and Department of Chemistry, Rice University , Houston, Texas 77005, United States.
authors.forename: Boris I
authors.initials: BI
authors.lastname: Yakobson
keywords: Hexagonal boron nitride; Wulff construction; crystal growth; density functional theory calculations; kinetics; morphology