Photoelectric properties of Cu2ZnSnS4 thin 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 Cu2ZnSnS4（CZTS） were produced by sulfurizing the precursors in a sulfur atmosphere at a temperature of 550℃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 x 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 x 1016 cm-3,6.96Ω-cm,and 12.9 cm2/（V-s）,respectively and the conduction type is p-type.Therefore,the CZTS thin films are suitable for absorption layers of solar cells.