Influence of Proton Ion Irradiation on the Linear–Nonlinear Optoelectronic Properties of Sb40Se20S40 Thin Films at Different Fluences for Photonic Devices

This study investigates the effects of 30 keV proton ion irradiation on the structural, morphological, and linear–nonlinear optoelectronic properties of Sb40Se20S40 thin films. The retention of an amorphous nature and vibrational bonding rearrangements caused by ion irradiation demonstrate structural tailoring. The cumulative decrease in roughness with an increase in ion dose decreases the surface energy and optical absorption loss. With the blue shifting of the absorption edges, proton irradiation increased the optical transmittance and reflectance. The variation of fluence changes the optical bandgap and Urbach energy, which are induced by local structural changes caused by defects and disorder. The refractive index decreased considerably, which supports the Moss rule. Proton irradiation reduced the interband transition and average band energy gap of the system. However, ion irradiation increased optical losses while decreasing optical conductivity and dielectric characteristics. The third-order nonlinear susceptibility and nonlinear refractive index decreased significantly as the fluence increased. Such materials with optical tuning capabilities via ion fluence are essential for cutting-edge photonic and optoelectronic applications.