Modifications in the structural,morphological, optical properties of Ag45Se40Te15 thin films by proton ion irradiation for optoelectronics and nonlinear applications

This current work reports the 30 keV proton ion irradiation induced structural, morphological, and optical properties change in Ag₄₅Se₄₀Te₁₅ films at different fluences. The thin films were irradiated with different ion fluences, such as 5 × 10¹⁵ ions/cm²,1 × 10¹⁶ ions/cm² and 5 × 10¹⁶ ions/cm². The electronic loss (S_e) dominates over the nuclear loss (S_n) in proton irradiation. The X-ray diffraction study shows the phase transformation from amorphous to crystalline upon ion irradiation. The Raman analysis confirms the change in chemical and vibrational bonds due to structural alterations in the films. The surface morphology has been studied by field emission scanning electron microscopy and the composition of the films has been checked by the energy dispersive X-ray analysis. The particle size increased upon the increase in ion irradiation fluence. The surface roughness of the films has been studied by atomic force microscopy. The transmission data is used to calculate the linear optical parameters. The absorption edge shifts towards the high wavelength region inferring the reduction in the optical bandgap. The linear refractive index of the films increased with ion fluence. The optical density increased at the high wavelength region while the skin depth decreased with fluence. The carrier concentration per effective mass decreased while the plasma frequency increased with proton irradiation. The nonlinearity (χ ⁽³⁾ and n₂) values increased significantly with the increase in fluences. Such kind of materials with optimization in their optical parameters are primarily essential for cutting-edge photonic, optoelectronic, and nonlinear optical applications.