Amorphous chalcogenide semiconducting materials are very sensitive to electromagnetic radiation and are useful for infrared optics and play a pivotal role in modern technology. In the present article, As2Se3 and bilayer Bi/As2Se3 thin films were prepared by thermal evaporation method. The 532 nm laser induced diffusion of active Bi top layer into barrier As2Se3 film was probed through spectroscopic techniques. An X-ray diffraction study reveals no structural change due to laser irradiation while the optical parameters are affected by both Bi addition and laser irradiation which brings a change in the transmittivity and absorption coefficient. The indirect optical band gap is found to be decreased by 0.11 eV due to Bi addition to As2Se3 which is explained on the basis of density of defect states with an increase in disorder. The laser irradiated Bi diffusion increases the optical band gap by 0.05 eV (photobleaching) with a decrease in disorder. The Tauc parameter and Urbach energy which measures the degree of disorder change with Bi doping and irradiation. The refractive index is modified by the illumination process which is useful for optical applications. The optical property change is well supported by X-ray photoelectron core level spectra and Raman spectra.

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Optical band gap tuning by laser induced Bi diffusion into As2Se3 film probed by spectroscopic techniques

Growth and characterization of ZnxCd1−xS nanoflowers by microwave-assisted chemical bath deposition

The present study reports the linear and nonlinear optical properties of as-prepared and annealed As40Se50Te10 thin films prepared on glass substrate by thermal evaporation method. The modifications in different properties after annealing were studied by XRD, EDAX, Raman spectroscopy, FESEM and UV–Vis-NIR and XPS spectroscopy. The study reports the decrease in optical band gap due to increase in disorder while the width of the tail in the gap increased with annealing temperature. The linear refractive index, optical as well as electrical conductivity and extinction coefficient increased with annealing. The dispersion energy, oscillator energy, dielectric constant and oscillator strength increased with annealing temperature while the electrical susceptibility decreased upon annealing. The 3rd order optical susceptibility and nonlinear refractive index were found to be increased with annealing temperature. The influence of different annealing temperatures on the variation of different parameters were elaborately explained on the basis of defect states in localized region. The structure remained unchanged while the heteropolar to homopolar bond conversion was noticed from the XPS and Raman spectroscopy. The changes in both nonlinear and linear optical properties by annealing shows that annealing temperature can be used as an important tool for controlling the optical constants of As40Se50Te10 chalcogenide film which could be a suitable candidate for numerous photonic applications.

Optimization of linear and nonlinear optical parameters of As40Se50Te10 thin films by thermal annealing

Thermal annealing induced evolution of AgIn5Se8 phase from Ag/In2Se3 bilayer thin film

In the present work, we report the change in optical parameters due to the deposition and photo-induced diffusion of Te layer into the chalcogenide As2Se3 film. The photo-diffusion creates a solid solution of As–Se–Te which has potential application in optical devices. The Te/As2Se3 bilayer films prepared by thermal evaporation technique were studied by various experimental techniques. The photo-diffusion of Te into As2Se3 matrix was done by 532-nm laser irradiation. The structure of the As2Se3, as-prepared and irradiated Te/As2Se3 films was studied by X-ray diffraction which were amorphous in nature. The presence of all the elements was checked by energy-dispersive X-ray analysis, and the optical transmission spectra were recorded by Fourier transform infrared spectrometer. The optical band gap is reduced by the deposition and diffusion of Te into As2Se3 film which is due to the increase in density of defect states in the gap region. The transmission is decreased, whereas the absorption efficiency is increased with the increase in disorderness. The X-ray photoelectron spectroscopy carried out on these films gives information about the bonding change due to the photo-diffusion process. Therefore, this is an important result which will open up new directions for the application of this material in semiconducting devices.

C. Kumar

Papers

Optical properties change in Sb40S40Se20 thin films by light-induced effect

Effect of Te addition on the optical properties of As2S3 thin film