Within first-principles calculations, we explore superconductivity in Ca-intercalated bilayer silicene compound, ${\mathrm{Si}}_2{\mathrm{CaSi}}_2$. This arises from the coupling of interlayer flowerlike $\mathrm{\Gamma }$-centered Fermi surface formed by the hybridization of Ca-3$d$ and Si-3$p_z$ orbitals with low-energy out-of-plane vibrations enabled by silicene's buckling. The consequent large electron-phonon coupling, as evident from the Eliashberg spectral function, leads to superconductivity below 12.5 K in this two-dimensional covalent system. Our results reveal the key control parameters to achieve superconductivity in experimentally synthesizable silicon-based thin materials that can find diverse applications.

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• Low-temperature superconductors
• Silicene
• Density functional theory
• Eliashberg theory