Formation of crystalline Si₉C₁₅ nano-islands and Si₉C₁₅/graphene heterostructures on Ru(0001)

Two-dimensional silicon carbides have attracted increasing interest due to their highly tunable band structures and rich physical properties. Among them, Si₉C₁₅ is particularly notable for its intrinsic auxeticity, strongly anisotropic carrier mobility, and pronounced optical and thermoelectric responses. However, the controlled growth of Si₉C₁₅ nano-islands has remained a challenge. Here, we report a novel growth technique for Si₉C₁₅ nano-islands. By exploiting the mild segregation of carbon atoms from a Ru(0001) substrate, we fabricate discrete, crystalline Si₉C₁₅ nano-islands at temperatures as low as ∼400 °C. Spectroscopic measurements reveal a spatial modulation of the local work function across the nano-island, which we attribute to the periodic potential landscape of the Si₉C₁₅ lattice. Furthermore, we demonstrate that this island morphology enables the construction of Si₉C₁₅/graphene lateral heterostructures. Our work establishes a new pathway for fabricating Si₉C₁₅ nanostructures as well as the heterostructures.