Synthesis of an optimized ZnS/Au/ZnS multilayer films for solar cell electrode applications

In this study, different film constructions (ZnS, ZnS/Au, and ZnS/Au/ZnS) were evaporated by thermal-evaporation. The study was conducted in order to identify the best film for solar cell applications. The study identifies ZnS (399.6 nm)/Au (18 nm) as the most appropriate film for further investigation because it shows a maximum optical band gap ≈ 3.43 eV and the minimum resistivity (0.46 × 10−3 Ω cm). It is noticed that the interference fringes disappeared due to the addition of the Au layer. The absorption edge was shifted towards a lower energy as the Au increased. The band gap Eg and resistivity ρRt were 3.49 eV and 0.12 × 10−3 Ωcm respectively. The refractive index increased up to the maximum value 6.2. The ZnS (399.6 nm)/Au (6 nm)/ZnS (399.6 nm) films exhibited amorphous structure, and with the increase of the Au thickness layer, the diffraction peaks related to FCC phase of the Au appeared. The film ZnS (399.6)/Au 18/ZnS (399.6) shows very promising parameters. The bandgap Eg is 3.38 eV, the sheet resistance is 1.53 × 10−3 Ω, the figure of merit equals 3.7 × 10−3 Ω−1 and the refractive index is 6.20. The results prove that the film ZnS (399.6)/Au 18/ZnS (399) is suitable for conductive electrodes in solar cells.