Growth and characterization of Sb 2 (S x Se 1-x ) 3 thin films prepared by chemical-molecular beam deposition for solar cell applications

Abstract

Antimony sulfide selenide, Sb 2 (S x Se 1-x ) 3 (x = 0–1), is a tunable bandgap compound that combines the advantages of antimony sulfide (Sb 2 S 3 ) and antimony selenide (Sb 2 Se 3 ). 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, Sb 2 (S x Se 1-x ) 3 thin films were deposited by chemical-molecular beam deposition on soda-lime glass substrates using anti- mony (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, Sb 2 (S x Se 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 Sb 2 Se 3 , Sb 2 S 3 and their ternary compounds Sb 2 (S x Se 1-x ) 3 . The optical characterization revealed a high absorption coefficient of 10 5 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.