On annealing induced effect in optical properties of amorphous GeSeSn chalcogenide films for optoelectronic applications

Thin films of GeSeSn were deposited by an evaporation technique. The X-ray diffraction studies demonstrate that the as-deposited and annealed films are amorphous in nature. Some optical constants were calculated for these films at an annealing temperature of 373 and 473 K. Dispersion of the refractive index is described utilizing the single oscillator model. In addition, the third-order nonlinear susceptibility and the nonlinear refractive index are calculated. The absorption coefficient of these films revealed an indirect optical band gap with a value of 1.03 eV, which is slightly increased by annealing. Also, it is found that the annealing decreases the width of the tail of localized states indicating a decrease in the disorder in GeSeSn films.