Author(s): Wu Xinkun, Liu Wei, Cheng Shuying, Lai Yunfeng, Jia Hongjie
Sn/Cu/ZnS precursor were deposited by evaporation on soda lime glass at room temperature, and then polycrystalline thin films of Cu2ZnSnS4 (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 × 104 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 × 1016 cm−3, 6.96 Ωcenterdotcm, and 12.9 cm2/(Vcenterdots), respectively and the conduction type is p-type. Therefore, the CZTS thin films are suitable for absorption layers of solar cells.