On the Band Gap of AgSbSe2

Spectroscopic ellipsometry studies of AgSbSe 2 are conducted, and the spectra of the permittivity and optical constants in the energy range 0.07–6.5 eV are determined. To describe the experimental spectra, the Tauc–Lorentz, modified Forouhi–Bloomer, and Cody–Lorentz models are used. It is found that the Cody–Lorentz model more adequately describes the near-edge region of the spectra of optical constants. It is shown that the optical properties, the shape of the absorption edge, and the structure of the band gap are substantially influenced by the spatial structural disorder of AgSbSe 2 crystals. From analysis of the experimental spectra by different methods, the band gap of AgSbSe 2 , E g , is determined: E g = 0.32 eV.