Laser-irradiated Ag/Sb20S40Se40 heterostructure film for enhanced photodetector application

Abstract

Ag/Sb₂₀S₄₀Se₄₀ heterostructure films were fabricated by thermal evaporation and modified through 532 nm laser irradiation at varying durations (0–90 min) to investigate their optoelectronic properties. Structural analysis confirmed the films remained amorphous after irradiation, while FESEM and TEM studies revealed distinct surface morphology modifications. Contact angle measurements showed a transition from hydrophilic (67°) to nearly hydrophobic (89°), enhancing self-cleaning potential. Optical characterization demonstrated a blue shift in the absorption edge, with the bandgap widening from 1.437 eV to 1.542 eV, alongside a decrease in Urbach energy from 324 meV to 262 meV, indicating reduced defect density and improved structural order. Transmittance increased from 88 % to 97 %, accompanied by decreased extinction coefficient and optical conductivity. Dielectric studies revealed lower dielectric loss with an increased quality factor, while nonlinear optical analysis showed a reduction in χ(3) from 8.68 × 10⁻¹¹ to 5.31 × 10⁻¹¹ esu and n₂ from 1.02 × 10⁻⁹ to 6.66 × 10⁻¹⁰, with a corresponding enhancement in the figure of merit. Photodetection performance was markedly improved after 90 min irradiation, with photosensitivity rising from 91 % to 162 %, responsivity from 1.37 × 10⁻⁸ to 2.07 × 10⁻⁶ A W⁻¹, and detectivity from 2.02 × 10⁶ to 2.91 × 10⁷ Jones. These results establish laser irradiation as an efficient route to engineer the optical and electronic behavior of Ag/Sb₂₀S₄₀Se₄₀ films for advanced optoelectronic and UV photodetector applications.