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Posted: Aug 22, 2017
Meter-sized single-crystal graphene growth becomes possible
(Nanowerk News) "Preparation determines the future". Since the discovery of graphene, the synthesis of graphene has long been a hot spot in graphene community. Using transition metals such as Cu or Ni as substrate, scientists have realized the preparation of large-area graphene films. Especially, high-quality large-scale continuous monolayer graphene has been successfully grown on Cu foils. This simple and low-cost method has been widely accepted as the most promising way for industrial-level graphene production.
However, graphene films obtained by this method are usually polycrystalline with domain boundaries, which would greatly degrade the electrical, mechanical, thermal and optical properties.
Therefore, to find a method to synthesize large-size single-crystal graphene is a big scientific problem needed to be solved.
These are schematic diagrams for epitaxial growth of single-crystal graphene on industrial Cu foil. (Image: Science China Press)
They first transformed industrial polycrystalline Cu foils into single-crystal Cu(111) by thermal annealing using a temperature-gradient-driving technique. Graphene domains were epitaxially grown on the Cu(111) substrate and then seamlessly merged together to form a large single-crystal graphene films.
Combined with their ultrafast graphene growth technique (Nature Nanotechnology, "Ultrafast growth of single-crystal graphene assisted by a continuous oxygen supply"), the graphene growth rate and each individual graphene domain size were improved obviously. Also, oxygen released from oxide at high temperature was proved to further improve the domain alignment, which would greatly improve the quality of graphene films.
This reported technique allows the synthesis of large-size single-crystal graphene films, which possess superior properties for various high-end applications, especially in electronics, such as large-scale fabrication of THz devices and the transparent film replacing ITO. It will also enable the epitaxial growth of various other 2D single-crystal materials on graphene with meter-sized dimension.