Isotropic Growth of Graphene toward Smoothing Stitching

Abstract

The quality of graphene grown via chemical vapor deposition still has very great disparity with its theoretical property due to the inevitable formation of grain boundaries. The design of single-crystal substrate with an anisotropic twofold symmetry for the unidirectional alignment of graphene seeds would be a promising way for eliminating the grain boundaries at the wafer scale. However, such a delicate process will be easily terminated by the obstruction of defects or impurities. Here we investigated the isotropic growth behavior of graphene single crystals via melting the growth substrate to obtain an amorphous isotropic surface, which will not offer any specific grain orientation induction or preponderant growth rate toward a certain direction in the graphene growth process. The as-obtained graphene grains are isotropically round with mixed edges that exhibit high activity. The orientation of adjacent grains can be easily self-adjusted to smoothly match each other over a liquid catalyst with facile atom delocalization due to the low rotation steric hindrance of the isotropic grains, thus achieving the smoothing stitching of the adjacent graphene. Therefore, the adverse effects of grain boundaries will be eliminated and the excellent transport performance of graphene will be more guaranteed. What is more, such an isotropic growth mode can be extended to other types of layered nanomaterials such as hexagonal boron nitride and transition metal chalcogenides for obtaining large-size intrinsic film with low defect.

The Way towards Ultrafast Growth of Single‐Crystal Graphene on Copper

“…In addition, the inhomogeneities influence the growth rate slightly by affecting the diffusion process 53, 54, 55, 56, 57. Proper surface treatment technique, like long‐time annealing,65 polishing,56, 68, 87 melting and resolidification,72, 73, 74 and the above mentioned special Cu stacking configuration can accelerate the graphene growth by minimizing surface roughness.…”

“…The growth of large‐area high‐quality graphene films is fundamental for the upcoming graphene applications. Chemical vapour deposition (CVD) method offers good prospects to produce large‐size graphene films due to its simplicity, controllability and cost‐efficiency 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75. Many researches have verified that graphene can be catalytically grown on metallic substrates, like ruthenium (Ru),13, 14 iridium (Ir),15, 16 platinum (Pt),17, 18, …”

Vapor‐phase growth of high‐quality wafer‐scale two‐dimensional materials

“…The most prevailing one is to suppress nucleation or even allow only one nucleus to grow into a wafer‐scale 2D film . Another vital approach is to “seamless stitch” multiple aligned islands into single‐crystal 2D materials over wafer scale . The third one is triggering the ESG to achieve the nearly single‐crystal 2D materials .…”

“…Compared with solid metal, the atoms in liquid metal tend to move intensely and arrange in an amorphous and isotropic way. The ultrasmooth and fluent surface will not induce any specific grain orientation or dominant growth rate toward a certain direction, which is beneficial for the isotropic growth . The rheological property also provides an ideal platform for the interaction‐driven rotation, alignment, and movement of grains, leading to the self‐assembly of the 2D crystals.…”

“…They also realized the self‐assembly of Al 2 O 3 nanoparticles on liquid metal surface triggered by an electrical charge, and laid the foundation for the precise control of graphene nucleation, finally leading to a graphene single‐crystal array at a very large size . Importantly, they designed the isotropic growth of graphene single crystals on liquid Cu and achieved the smoothing stitching of adjacent graphene domains (Figure A‐C) . The as‐grown graphene grains are isotropic round with mixed smooth edges that exhibit high activity.…”