Structural, optical, and electrical properties of Cu2SnS3 thin films produced by sol gel method

Abstract

The structural, optical, and electrical properties of p-type Cu₂SnS₃ thin films produced by the deposition of a dimethylsulfoxide-based sol gel solution using the centrifugation on substrates with subsequent heat treatment of the layers formed have been studied. The conditions of formation of the films using low-temperature short-time treatments in open atmosphere and a final annealing in a low vacuum (0.1 Pa) have been analyzed. The crystallite sizes D ~ 42 nm in the polycrystalline films have been found using X-ray phase analysis. Their compositions have been confirmed using the Raman spectra and the energy-dispersive X-ray analysis. The optical forbidden band width of direct allowed (E_g^d ~ 1.25 eV) and direct forbidden (E_g^df ≈ 0.95 eV) optical transitions have been determined as a result of the light transmission and absorption. Based on the study of the electrical properties using a model of polycrystalline materials, the validity of the produced films with resistivity ρ ≈ 0.21 Ω cm, the hole concentration p₀ ≈ 1.75 × 10¹⁹ cm^–3, and the effective mobility μ_p ≈ 1.67 cm²/(V s) for manufacturing solar cells.