| Summary: | The substrate/(200–900 nm) Al:ZnO (AZO)/15 nm Zn films were deposited on glass substrates at room temperature by magnetron sputtering, followed by a face-to-face annealing in vacuum. The effect of AZO thickness and the annealing treatment on the structure, morphology and electrical properties of the bilayer films was discussed. All the samples show a hexagonal wurtzite structure with (0 0 2) preferred orientation and the annealed samples have a uniform surface morphology and low surface roughness (∼1 nm). Compared with as-deposited films, annealed films present a significant increase in the carrier concentration, which can be attributed to the effective elimination of Zn-vacancy defects by successfully introducing Zn atoms into AZO layers. The lowest resistivity of 3.36 × 10−4 Ω cm with carrier concentration of 1.67 × 1021 cm−3 can be obtained. In addition, based on the results of above experiments, the Zn + AZO multilayer films with four different Zn diffusion models were fabricated. The average visible transmittance of the films is in the range of 79.1–85.2%. The substrate/AZO/Zn model has the optimum electrical performance, while the substrate/AZO/Zn/AZO model exhibits the highest optoelectronic figure of merit of 3.47 × 103 Ω−1 cm−1. Keywords: Aluminum doped zinc oxide thin films, Magnetron sputtering, Zinc diffusion, Optoelectronic properties
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