Optical Characterization of Ge30-xSbxTe10Se60(0 ≤ x ≤ 20) Thin Films for Optoelectronics

The quenching procedure has been utilized for the preparation of the bulk of chalcogenide glasses Ge 30-x SbxTe10 Se60 where mass% (x =0, 5, 10, 15, 20), the samples were made into thin films using the thermal evaporation method. The optical characterization of the films was performed using a two-beam spectrophotometer with a 400–2500 nm wavelength range. The refractive index n was deduced, it showed that n increased with increasing Sb concentration. The optical band gap Eg was observed to decrease as Antimony concentration increased, where Eg falls from 1.375 to 1.009 eV. This decrease in Eg is described by the average single bond energy, Urbach energy, where the average single bond energy falls from 23.55to 19.87 Kcal g-1 at-1 as Sb content increases, and Urbach energy rises from 0.29 to 0.4 eV as Sb content increases. For all the samples, raising incoming photon wavelength causes the real and imaginary components of the dielectric constant diminish., whereas increase with increasing Sb doping rate. Wemple and DiDomenico dispersion model was utilized to calculate the dispersion parameters for incontent.e single-oscillator energy E0, the dispersion energy Ed, and the static refractive index no; it was found that the values of E0 roughly match the energy gap's twofold value, and the values of Ed and E0 fall as the antimony content rises , where Ed value falls from 26.47 eV to 20.19 eV , and the value of E0 falls from 3.89 to 2.62 eV while no increase from 2.796 to 3.022 with increasing Antimony content . The loss factor's estimated values demonstrate an increase as photon energy rises, as well as an increase in antimony content. An increase in non-linear refractive index n2 as antimony concentration increases where n2 rises from 1.99x10-10 to 3.73x10-10 esu. Their entire potential for nonlinear optics may be found in the mid-infrared region due to their low optical band gap energy. These materials
Karrar et al., 2023
pg. 76
have wide IR transparency and high (non)linear refractive indices, which make them desirable for optical nonlinear devices.