Stability of Ag2S/As2Se3 thin films under time dependent laser irradiation and its impact on linear-nonlinear optical properties for optoelectronic applications

The time dependent laser induced effects on the linear and nonlinear optical properties of Ag2S/As2Se3 heter-ostructure films has been investigated in the current study. The Ag-S-Se-As solid solution formed from the intermixing of Ag2S and As2Se3 layers brings changes in the absorption edge and other optical parameters. The increase in transmittance gradually saturated followed by small increase in absorbance. The reduction in bandgap from 1.572 eV to 1.52 eV is due to the increase in defect states and disorder in the film because of the intermixing of two layers. The static refractive index is increased by 6.03% which enhanced the nonlinear refractive index by 38% upon laser irradiation. The optical conductivity increased while the electrical suscep-tibility decreased with the increase in laser irradiation time duration. The dielectric loss factor increased that reduced the quality factor. The increase in carrier concentration reduced the optical electronegativity upon laser irradiation. The third order nonlinear susceptibility (chi(3)) is doubled at 120 min. laser irradiation. The amorphous nature remains unchanged with laser irradiation as probed by XRD and Raman study. The surface roughness is not much changed as found from AFM study. The stability in structure and morphology of the films make them appropriate candidate for optoelectronic applications, in particular those exposed frequently to laser source.

Automated summary

The study investigates the time dependent laser induced effects on the linear and nonlinear optical properties of Ag2S/As2Se3 heterostructure films. The intermixing of Ag2S and As2Se3 layers forms an Ag-S-Se-As solid solution, which leads to changes in absorption edge and other optical parameters. The transmittance gradually saturates while the absorbance slightly increases. Changes in film's structure result in a reduction in bandgap and an increase in static refractive index and nonlinear refractive index upon laser irradiation. The film's stability and morphology make it suitable for optoelectronic applications, especially under laser exposure.