Effect of heat treatment on infrared reflection property of Al-doped ZnO films

• Infrared reflection of AZO films was investigated from 1.5 μm to 25 μm.
• Infrared reflection of AZO films was closely related to annealing temperature.
• Infrared reflection was inversely proportional to film resistivity.
• AZO film with infrared reflection about 40% was prepared by annealing at 300 °C.

Al-doped ZnO (AZO) films were prepared on glass substrates by radio frequency (RF) magnetron sputtering technology. Crystal structure, surface morphology, electrical properties and infrared reflection of the AZO films were systematically investigated by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Hall measurement system and Fourier Transform infrared spectroscopy, respectively. In addition, the corresponding properties of AZO films annealing at different temperatures ranging from room temperature to 400 °C were also analyzed. The results indicate that the prepared AZO films exhibit highest ZnO (0 0 2) peak intensity and lowest electrical resistivity after annealing at 300 °C. And AZO film with a low resistivity value of 0.0185 Ω-cm, a relatively high average infrared reflection of 40% can be acquired after the films were annealed at 300 °C. The high infrared reflection property of the AZO film makes it a promising candidate for future heat shielding film.