Effect of 3 MeV proton ion irradiation on optical properties of Se₇₀Te₂₀Sn₁₀ thin films for photonic applications

The influence of proton irradiation on the optical, dielectric, and structural characteristics of Se₇₀Te₂₀Sn₁₀ thin films was systematically examined. These films were fabricated using electron-beam evaporation and subsequently 3 MeV proton irradiation at fluence levels ranging from 5 × 10¹³ to 5 × 10¹⁶ ions/cm². X-ray diffraction analysis confirmed the amorphous nature of the films, while UV–Vis–NIR spectroscopy demonstrated a modifiable optical band gap that decreased from 1.84 eV to 1.61 eV with increasing fluence, followed by partial recovery at higher doses. The dielectric constant showed significant enhancement, peaking at 5 × 10¹³ ions/cm², and recovering at 5 × 10¹⁶ ions/cm², suggesting structural reorganization within the material. Surface morphology investigations using AFM revealed increased roughness parameters, such as SA and SQ, with fluence, which were closely linked to trends observed in the optical and dielectric properties. These findings underscore the suitability of Se₇₀Te₂₀Sn₁₀ thin films for radiation-resistant photonic and optoelectronic technologies, with the fluence-dependent recovery offering valuable insights into defect dynamics and the material's robustness under irradiation.