Growth and characterization of Sb2(SxSe1-x)3 thin films prepared by chemical-molecular beam deposition for solar cell applications

Antimony sulfide selenide, Sb₂(S_xSe_1-x)₃ (x = 0–1), is a tunable bandgap compound that combines the advantages of antimony sulfide (Sb₂S₃) and antimony selenide (Sb₂Se₃). This material shows great potential as a light-absorbing material for low-cost, low-toxicity, and highly stable thin-film solar cells. In this study, Sb₂(S_xSe_1-x)₃ thin films were deposited by chemical-molecular beam deposition on soda-lime glass substrates using antimony (Sb), selenium (Se), and sulfur (S) precursors at a substrate temperature of 420 °C. By independently controlling the source temperatures of Sb, Se, and S, Sb₂(S_xSe_1-x)₃ thin films with varying component ratios were obtained. Scanning electron microscopy revealed significant changes in the surface morphology of the films depending on the elemental ratio of [S]/([S]+[Se]). Crystallites shaped like cylindrical microrods with d = 0.5–2 µm diameter and l = 3–5 µm length were grown at a certain angle on the substrate. X-ray diffraction patterns showed peaks corresponding to the orthorhombic structures of Sb₂Se₃, Sb₂S₃ and their ternary compounds Sb₂(S_xSe_1-x)₃. The optical characterization revealed a high absorption coefficient of 10⁵ cm⁻¹ in the visible and near-infrared light regions. The band gap of the compounds changed almost linearly from 1.2 eV to 1.36 eV with a change in the ratio of elements [S]/([S]+[Se]) from 0.03 to 0.08.