Effect of aluminum-nano structures on the optoelectronic and structural properties of the AZO layer with various substrate heating temperatures

In this study, Al doped ZnO layers are deposited on glass substrates with various substrate heating temperatures, using RF magnetron sputtering. The conductivity, microstructure and optoelectronic properties are investigated. X-ray diffraction and field emission scanning electron microscopy are used to analyze the crystal orientation and structural characteristics. The optoelectronic properties are measured by UV–Vis–NIR spectroscopy and Hall effect measurement, respectively. The results show that the preferred orientation of the ZnO crystal is changed for different substrate heating temperatures. For lower temperatures, between 200 and 400 °C, the main peak is located at (103) and at substrate temperatures of more than 400 °C, the main peak returns to (002). A comparison of the different substrate heating conditions shows that the conductivity obviously increases with the substrate heating temperatures, especially at 300 °C, where the lowest resistance of 2.356 × 10⁻³ Ω is achieved, and the average transmittance in visible light, from 400 to 800 nm, is about 92 %. Well-distributed Al nano-structures with lower density are observed by high-resolution transmission electron microscopy, which play an important role.