Synthesis of uniform nanometer-thick graphite film on polycrystalline Ni substrate with ultrafine grains

• Published in: Carbon (New York) 2021-06, Vol.177, p.35-43
• Main Authors: Hu, Qicheng, Nam, Ki-Bong, Yeo, Jin-Ho, Kim, Mun-Ja, Yoo, Ji-Beom
• Format: Article
• Language: English
• Subjects: Annealing; Buffer layers; Carbon; Carbon diffusion; Chemical synthesis; Chemical vapor deposition; Film thickness; Grain growth; Grain orientation; Graphene; Graphite; Low temperature; Metal foils; Morphology; Motion pictures; Multilayers; Ni substrate; Nickel; Orientation effects; Polycrystals; Substrates; Supersaturation; Thick films; Thin films; Ultrafine grains; Ultrafines
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2021.02.058

When a polycrystalline Ni foil is used as the substrate for the chemical vapor deposition synthesis of multilayer-graphene or nanometer-thick graphite films (NGFs), these films always exhibit uneven morphologies and qualities on Ni grains with different orientations. In this study, we fabricated a carbon-supersaturated Ni foil (ss-Ni foil) to function as a carbon source through an ultrafast cooling process (∼180 °C/s), while an additional Ni film was sputtered on the ss-Ni foil to act as a buffer layer and a new surface for NGF growth. By re-annealing the Ni film/ss-Ni foil system at a low temperature (∼650–800 °C) within a short duration, NGF can rapidly form on the Ni film owing to the high supersaturation degree of the ss-Ni foil. The grain growth of the Ni film is limited by the low-temperature growth process, and the ultrafine grains of Ni film averaged the grain orientation effect from the Ni foil. The NGF formed on the Ni film/ss-Ni foil showed a significant improvement in thickness and quality uniformity, and we studied the influences of Ni film thickness as well as re-annealing temperature and time on the diffusion of carbon in the Ni film/ss-Ni foil system and summarized the growth mechanism. [Display omitted]