Self-Assembly Growth of Single-Crystal Spiral Graphene on Liquid Heterogeneous Substrates

• • Growth temperature of 1083 °C (melting point of Cu) ensures a fully molten Cu layer on solid Ni, enabling spiral graphene growth; this liquid-phase condition is essential, as control experiments on solid Cu-Ni alloys yield no spiral morphology. • • A 30-minute growth time under CVD conditions yields single-crystal spiral graphene with uniform Bernal stacking, confirmed by TEM and SAED; this precise stacking is critical for reproducible electronic band structure in device applications. • • ToF-SIMS depth profiling and isotope-labeling experiments demonstrate that carbon incorporation occurs at spiral step edges, revealing a self-assembly mechanism that enables controlled layer-by-layer growth—a key advantage over conventional solid-substrate CVD. • • The liquid heterogeneous substrate (Cu on Ni) provides a dynamic surface that enhances carbon diffusion and step-edge kinetics, achieving single-crystal quality without the need for complex seed engineering, thereby reducing manufacturing cost and complexity.