Optimization of linear and nonlinear optical parameters in As₄₀Se₆₀ film by annealing at different temperature

The present research reports the influence of different annealing temperature on the linear and nonlinear optical response of thermally evaporated 800 nm As₄₀Se₆₀ thin films. The optical parameters were deduced from the transmittance and reflectance spectra using spectrophotometric measurements in the range 500–1000 nm. The heat treatment is found to be significantly enhanced both linear and nonlinear refractive index as well as absorption coefficient. The optical bandgap is found to be systematically decreased with annealing temperature. The large covalently bonded molecules of the films were seemingly favourable for the increase of nonlinear optical susceptibility. The developments of linear, nonlinear optical parameters, as well as the optical conductivity by annealing process, infers that annealing temperature can be considered as a useful factor for controlling the optical properties of the As₄₀Se₆₀ chalcogenide film which could be candidate for numerous photonic applications. The structural study was done by X-ray diffraction and Raman spectroscopy.