Ultraflat Cu(111) foils by surface acoustic wave-assisted annealing

B Tian and JZ Li and QX Wang and A Samad and Y Yuan and MN Hedhili and A Jangir and M Gruenewald and MR Lanza and U Schwingenschloegl and T Fritz and XX Zhang and Z Liu, NATURE COMMUNICATIONS, 15, 9488 (2024).

DOI: 10.1038/s41467-024-53573-y

Ultraflat metal foils are essential for semiconductor nanoelectronics applications and nanomaterial epitaxial growth. Numerous efforts have been devoted to metal surface engineering studies in the past decades. However, various challenges persist, including size limitations, polishing non-uniformities, and undesired contaminants. Thus, further exploration of advanced metal surface treatment techniques is essential. Here, we report a physical strategy that utilizes surface acoustic wave assisted annealing to flatten metal foils by eliminating the surface steps, eventually transforming commercial rough metal foils into ultraflat substrates. Large-area, high-quality, smooth 2D materials, including graphene and hexagonal boron nitride (hBN), were successfully grown on the resulting flat metal substrates. Further investigation into the oxidation of 2D-material-coated metal foils, both rough and flat, revealed that the hBN-coated flat metal foil exhibits enhanced anti- corrosion properties. Molecular dynamics simulations and density functional theory validate our experimental observations. Ultraflat metal foils are important for the growth of high quality 2D materials, but their fabrication remains challenging. Here, the authors report a surface-acoustic-wave-assisted annealing method to flatten the surface of commercial Cu foils, leading to the growth of 2D graphene and hexagonal boron nitride with enhanced anti-corrosion properties.

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