Effects of Magnetron Sputtering Process on Deposition of Cu₂ZnSnS₄ Film on Al Foil

Cu₂ZnSnS₄（CZTS） films were prepared on Al substrates by magnetron sputtering and post-sulfurization. The effects of metal precursor stacking structure and sputtering time on the quality of CZTS films deposited on Al substrates were studied. X-ray diffraction（XRD） and Raman spectra show that all samples have a kesterite-type CZTS phase. Scanning electron microscopy（SEM） and X-ray energy dispersive spectroscopy（EDS） shows that there is no Al₂S₃ phase layer at the Al/CZTS interface of all samples. The current-voltage（I-V） characteristic curve shows that the Al/CZTS interface forms ohmic contact. The above experimental results prove the feasibility of Al as the substrate and back electrode of CZTS film. In addition, Raman spectroscopy and EDS confirm the presence of a significant Cu_xS secondary phase on the surface of the films for Al/Cu/Zn/Sn/Cu and Al/Zn/Sn/Cu/Zn stacked structures, whereas no Cu_xS secondary phase is observed for the Al/Zn/Sn/Cu stacked structure. Moreover, with the increase of sputtering time, the sample film becomes smoother, the crystallinity of CZTS phase increases first and then decreases, the secondary phase of Sn₂S₃ decreases, and the structural resistance of CZTS/Al decreases first and then increases.