Abstract: In order to study the effect of trace Ni-doping on the crystallinity, defect concentration and electrical properties of Cu₂ZnSn(S,Se)₄ thin films, without affecting other cations (Cu,Zn and Sn), we introduced trace Ni ions into the Cu₂ZnSnS₄ precursor solution, and prepared the Ni-doped Cu₂ZnSn(S,Se)₄ films through a spin-coating, sintering and selenization process. We conducted testing and analysis by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectrometry, scanning electron microscopy, UV-Vis spectrophotometry, Hall effect and conductive atomic force microscopy. The results show that when the Ni-doping percentage is 0.5%，the film achieves optimal crystallinity and the concentration of deleterious Sn_Zn defect is minimized. The carrier concentration is 3.58×10¹⁶ cm^-3,  the average surface current is 4.67 nA, and the electrical properties of the film reach its optimum.

Key words: Cu₂ZnSn(S,Se)₄ thin film, Ni-doping, defect concentration, electrical property