Al-doped ZnS thin films for buffer layers of solar cells prepared by chemical bath deposition

In this reported study, Al-doped ZnS (ZnS:Al) thin films were fabricated by chemical bath deposition in alkaline condition along with a stable complexing agent of sodium citrate in ammonia/ammonium chloride buffer solution. Al concentrations were varied from 0 to 10 at.%. The structure and composition of the films were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra and Raman spectroscopy. The XRD, FTIR and Raman spectra confirmed the existence of ZnS and Al-S bond, which had some effects on the properties of the films. The optical characteristics indicated the changes of the bandgap with the Al-doping concentrations. The resistivity of the ZnS:Al films with different Al-doping concentrations after annealing was analysed and the sample with 6 at.% Al concentration had the lowest resistivity of 9.9 × 10⁴ Ω cm.