The realization of topological surface states and superconductivity within a single material platform is a crucial step toward achieving topologically nontrivial superconductivity. This can be achieved at an interface between a superconductor and a topological insulator or within a single material that intrinsically hosts both superconductivity and topological surface states. Here we use scanning tunneling microscopy to study ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x{\mathrm{Bi}}_2{\mathrm{Te}}_4$ crystals. Spectroscopic evidence reveals the coexistence of topological surface states and superconductivity on the same surface of the crystals. The Te-terminated surface exhibits a single U-shaped superconducting gap with a size of up to $311\mu \mathrm{eV}$, alongside Dirac bands outside the gap. Analysis of the vortex structure and differential conductance suggests weak-coupling $s$-wave superconductivity. The absence of observed zero modes suggests that shifting the Fermi level closer to the Dirac point of the topological bands is necessary to realize a topological superconducting state.

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• Superconductivity
• Surface states
• Topological superconductors
• van der Waals systems
• Angle-resolved photoemission spectroscopy
• Density functional calculations
• Scanning tunneling microscopy