About the band gap of the AgSbSe$_{2}$

Spectral ellipsometric studies of AgSbSe$_{2}$ have been carried out, and the spectra of optical constants and permittivity have been determined in the photon energy range of 0.07–6.5 eV. To describe the obtained spectra, the Tauc–Laurents, modified Forouhi–Bloomer and Cody–Laurents models were used. It was found that the Cody–Laurents model better describes the sub-edge region of the spectrum of optical constants. It is shown that the spatial structural disordering of AgSbSe$_{2}$ crystals has a significant effect on the optical properties, the shape of the absorption edge, and the structure of the band gap. Based on the analysis of the obtained spectra and using various methods, the band gap of AgSbSe$_{2}$, $E_g$ = 0.32 eV, was determined.