The Effect of Post Deposition Treatment on Properties of ALD Al-Doped ZnO Films

In this paper, aluminum-doped zinc oxide (ZnO:Al or AZO) thin films are grown using atomic layer deposition (ALD) and the influence of postdeposition UV-ozone and thermal annealing treatments on the films' properties are investigated. X-ray diffraction (XRD) revealed a polycrystalline wurtzite structure with a preferable (100) orientation. The crystal size increase after the thermal annealing is observed while UV-ozone exposure led to no significant change in crystallinity. The results of the X-ray photoelectron spectroscopy (XPS) analyses show that a higher amount of oxygen vacancies exists in the ZnO:Al after UV-ozone treatment, and that the ZnO:Al, after annealing, has a lower amount of oxygen vacancies. Important and practical applications of ZnO:Al (such as transparent conductive oxide layer) were found, and its electrical and optical properties demonstrate high tunability after postdeposition treatment, particularly after UV-Ozone exposure, offers a noninvasive and easy way to lower the sheet resistance values. At the same time, UV-Ozone treatment did not cause any significant changes to the polycrystalline structure, surface morphology, or optical properties of the AZO films.

Automated summary

In this paper, aluminum-doped zinc oxide (ZnO:Al or AZO) thin films were grown using atomic layer deposition (ALD), and the effects of postdeposition UV-ozone and thermal annealing treatments on the films' properties were investigated. X-ray diffraction (XRD) revealed a polycrystalline wurtzite structure with a preferable (100) orientation. Thermal annealing increased the crystal size, while UV-ozone exposure had no significant impact on crystallinity. X-ray photoelectron spectroscopy (XPS) analysis revealed a higher amount of oxygen vacancies in the ZnO:Al after UV-ozone treatment, while the ZnO:Al had lower oxygen vacancies after annealing. The important and practical applications of ZnO:Al were found, particularly for transparent conductive oxide layers with high tunability in electrical and optical properties after postdeposition treatment, especially UV-ozone exposure for reducing sheet resistance values. Meanwhile, UV-ozone treatment did not affect the polycrystalline structure, surface morphology, or optical properties of the AZO films.