Photoinduced changes in the linear and non-linear optical properties of Ge10In10Se80 thin films

Ge10In10Se80 thin films were deposited by thermal evaporation technique. X-ray diffraction confirmed the amorphous nature of the bulk and thin films. The effect of exposure time on the linear optical properties of Ge10In10Se80 thin films in the spectral range 400-2500 nm were studied. The spectral distribution of transmittance for virgin and illuminated Ge10In10Se80 films indicated a blue shift of the absorption edge (photobleaching). The shift increased with increasing the exposure time. The indirect band gap was found to be 1.99 eV for virgin films and increased to 2.06 eV after illuminated for 3 h. Smakula's equation was used to calculate the concentration of color centers appeared in the absorption curves. It was found to increase from 2.11 × 1018 m− 3 to 3.73 × 1018 m− 3 for films exposed to 1 and 3 h, respectively. The dispersion results of the refractive index were analyzed using the single oscillator model. The dispersion energy parameters were found to depend on the photobleaching phenomenon. The effect of exposure time on the non-linear optical parameters is studied using empirical relations.