In situ epitaxial engineering of graphene and h-BN lateral heterostructure with a tunable morphology comprising h-BN domains

Graphene and hexagonal boron nitride (h-BN), as typical two-dimensional (2D) materials, have long attracted substantial attention due to their unique properties and promise in a wide range of applications. Although they have a rather large difference in their intrinsic bandgaps, they share a very similar atomic lattice; thus, there is great potential in constructing heterostructures by lateral stitching. Herein, we present the in situ growth of graphene and h-BN lateral heterostructures with tunable morphologies that range from a regular hexagon to highly symmetrical star-like structure on the surface of liquid Cu. The chemical vapor deposition (CVD) method is used, where the growth of the h-BN is demonstrated to be highly templated by the graphene. Furthermore, large-area production of lateral G-h-BN heterostructures at the centimeter scale with uniform orientation is realized by precisely tuning the CVD conditions. We found that the growth of h-BN is determined by the initial graphene and symmetrical features are produced that demonstrate heteroepitaxy. Simulations based on the phase field and density functional theories are carried out to elucidate the growth processes of G-h-BN flakes with various morphologies, and they have a striking consistency with experimental observations. The growth of a lateral G-h-BN heterostructure and an understanding of the growth mechanism can accelerate the construction of various heterostructures based on 2D materials. 2D materials: Stitching graphene into a multi-functional quilt Graphene flakes can now be co-assembled with another nanomaterial into centimeter-scale sheets with promising optical and electrical properties. Hexagonal boron nitride (h-BN) is a light-responsive ceramic that has a similar 2D atomic lattice to high-conductivity graphene. A team led by Hui Ying Yang at the Singapore University of Technology and Design and Feng Ding from the Institute for Basic Science in Ulsan, South Korea, have now used liquefied copper as a confined growth environment to combine these two compounds. Exposing copper held at 1100 °C to methane vapors catalyzed the growth of tiny 2D graphene flakes in a thin surface region. Subsequent addition of boron nitride prompted lateral growth of h-BN crystals around the graphene flake edges. The researchers showed that by tweaking the chemical vapor conditions large-area graphene/h-BN structures across the whole substrate could be produced. In this work, the large-scale growth of latera