Post-Annealing Effect on the Physicochemical Properties of Sn-Te-O Thin Films

This study explores how post-deposition thermal annealing alters the structural, morphological, and electronic properties of Sn–Te–O thin films grown by radio-frequency magnetron co-sputtering. Thin films were annealed at temperatures ranging from 298 K to 873 K and analyzed using a suite of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Annealing at 473 K resulted in increased surface roughness (R_q) in Te-rich films, while higher annealing temperatures promoted a chemical shift in tin oxidation states from Sn²⁺ to Sn⁴⁺. XRD patterns of films annealed at 473 K revealed the emergence of cubic-phase SnTe reflections not prominent in unannealed samples. Contact angle measurements indicated enhanced wettability in high-Te films after annealing, and work function analysis via Kelvin probe showed a trend of decreasing surface potential with lower Te content. These results provide insight into the thermal oxidation behavior and surface evolution of SnTe films, relevant for thermoelectric and topological applications.