Optical and mechanical properties of Ag doped thermally evaporated SeTe thin films for optoelectronic applications

Se–Te materials have shown promise in optoelectronic applications. A combination of enhanced optical and mechanical properties represents a good candidate for optical limiting devices. Here, we report the influence of Ag additive on the optical and mechanical properties of (Se70Te30)100−xAgx(0.0≤x≤8.0at.%) chalcogenide thin films. The reflectance spectra of amorphous thin films have been analyzed in the spectral range 0.3 μm–2.5 μm. The optical parameters are obtained using reflectance spectra of the thin films. The refractive index increases with the addition of Ag, while the optical band gap decreases from 1.40 eV to 1.11 eV. The reduction in the optical band gap is correlated with the raise in the concentration of defect states and the disorder. The nonlinear refractive index and nonlinear susceptibility have been evaluated and found to show an augmented response with Ag content. The value of (χ(3)) increases from 3.44 × 10−11 esu to 7.66 × 10−11 esu and n2 from 3.98 × 10−10esu to 8.08 × 10−10esu. The mechanical properties have also been analyzed theoretically and ultrasonically with Ag incorporation to SeTe thin films.