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

Abstract

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.