Structural and spectroscopic ellipsometry studies on vacuum-evaporated Sn2m−4Sb4S2m+2 (m = 2.5, 3 and 4) thin films deposited on glass and Si substrates

摘要: Abstract Sn 2m−4 Sb 4 S 2m+2 (m = 2.5, 3 and 4) thin films were deposited on glass Si substrates using vacuum evaporation technique. The structural properties have been investigated by X-ray diffraction (XRD) Raman spectroscopy. XRD patterns revealed the polycrystalline nature of even when they are not heated during process. spectra four main peaks. units Sn–Sb–S tetrahedral [SnS ] pyramidal [SbS ]. cross-section morphology was obtained scanning electron microscopy (SEM). Spectroscopic ellipsometry (SE) measurements ( ψ Δ) carried out to study optical films. SE measured data analyzed considering double layer model for all samples, with two oscillators Tauc-Lorentz Gaussian dispersion relations. Surface roughness taken into consideration as shown in SEM micrographs. From ellipsometric study, we determined thicknesses modeled layers their parameters (refractive index, absorption coefficient …). All exhibit high α visible range (>10 5  cm −1 ). values band gap energy E g 1.52, 1.29 1.28 eV, respectively m = 2.5, 4. For samples silicon, (SnSb 7 ) = 1.29 eV, 2 ) = 1.13 eV (Sn ) = 1.48 eV.