Effect of SbSn additions on the physical characterization of amorphous Se

► The present work deals with the incorporation the optical properties of amorphous Se with SbSn. ► High accuracy determination of the film thickness and the complex index of refraction. ► The allowed non-direct electronic transitions are mainly responsible for the photon absorption in the investigated films. ► The changes in the refractive index were discussed in terms of the single-oscillator model (Wemple-DiDomenico relationship). ► The obtained results were discussed in terms of the chemical-bond approach.