Optimizing the Microstructures of Inclined Deposition to Improve the Photoelectric Properties of ZnO Thin Films

Abstract

Radiofrequency magnetron sputtering has been applied in the deposition of a zinc oxide (ZnO) thin film, which has been used as a next-generation transparent conducting electrode material to replace indium tin oxide. To improve the photoelectric properties of the ZnO thin film, an inclined process was used to modify the thin-film deposition. Specifically, the intermittent number and intermittent time were first adjusted to facilitate the formation of the thin film before the inclined fabrication. After the optimal angle of inclination was determined, rapid thermal annealing was used to further optimize the structure of the deposited thin film. After the fabrication process was finished, field-emission scanning electron microscopy and x-ray diffraction were used to measure and observe the crystallinity and surface morphology of the thin film. High-resolution transmission electron microscopy was used to analyze the microstructure of the thin film after inclined deposition. Hall effect analysis and ultraviolet–visible spectroscopy were also conducted to analyze the optical and electrical properties of the thin film. The results indicated that the thin film exhibited optimal photoelectric properties at an IN value of 1, an IT value of 7.5 min, and an angle of inclination of 40° during fabrication. After the thin film was treated using rapid thermal annealing at 800°C for 12.5 min, it was compared with the thin film that was not. The results indicated that the electrical resistivity of the thin film produced by inclined fabrication decreased from 1.78 × 10⁻¹ Ω cm to 8.69 × 10⁻² Ω cm. In addition, thermal annealing treatment further reduced the electrical resistivity of the thin film to 1.24 × 10⁻³ Ω cm. Calculation of the figure-of-merit of the thin film revealed that it increased from 1.40 × 10⁻⁵ Ω⁻¹ to 3.86 × 10⁻³ Ω⁻¹.