Photoelectric properties of Cu2ZnSnS4thin films deposited by thermal evaporation

Sn/Cu/ZnS precursor were deposited by evaporation on soda lime glass at room temperature, and then polycrystalline thin films of Cu 2 ZnSnS 4 (CZTS) were produced by sulfurizing the precursors in a sulfur atmosphere at a temperature of 550 °C for 3 h Fabricated CZTS thin films were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, ultraviolet-visible-near infrared spectrophotometry, the Hall effect system, and 3D optical microscopy. The experimental results show that, when the ratios of [Cu]/([Zn] + [Sn]) and [Zn]/[Sn] in the CZTS are 0.83 and 1.15, the CZTS thin films possess an absorption coefficient of larger than 4.0 × 10 4 cm −1 in the energy range 1.5–3.5 eV, and a direct band gap of about 1.47 eV. The carrier concentration, resistivity and mobility of the CZTS film are 6.98 × 10 16 cm −3 , 6.96 Ω·cm, and 12.9 cm 2 /(V·s), respectively and the conduction type is p-type. Therefore, the CZTS thin films are suitable for absorption layers of solar cells.