Raman scattering and spectroscopic ellipsometry studies of Sb₂S₃ and Sb₂Se₃ bulk polycrystals

Antimony sulfide (Sb₂S₃) and antimony selenide (Sb₂Se₃) compounds have attracted considerable attention for applications in different optoelectronic devices due to their notable optical and electrical properties, and due to the strong anisotropy of these properties along different crystallographic directions. However, the efficient use of these promising compounds still requires significant efforts in characterization of their fundamental properties. In the present study, Raman scattering and spectroscopic ellipsometry were used to investigate the vibrational and optical properties of Sb₂Se₃ and Sb₂S₃ bulk polycrystals grown by the modified Bridgman method. The first technique proved the presence of the desired Sb₂S₃ and Sb₂Se₃ phases in the analyzed ingots and confirmed the absence of any preferential crystallographic orientation at the measured surface of the samples. Spectroscopic ellipsometry was performed using a multi-oscillator Tauc-Lorentz dispersion model, and yielded a complex dielectric function of chalcogenides over the range 1.0-4.6 eV with a three phase model (ambient, surface and bulk materials). Finally, spectral data on the refractive index, the extinction coefficient, the absorption coefficient and the reflectivity at normal incidence, R, were obtained, which serve as a reference for the optical modeling of optoelectronic devices based on polycrystalline Sb₂S₃ and Sb₂Se₃ compounds.