Presentation Information
[25p-61A-2]Investigating the Role of Hydrogen on RF-Sputtered Al-Doped ZnO Thin Films
〇(M2C)MuhammadFaizRHasian Rambey1, Takaya Ogawa1, Hideyuki Okumura1 (1.Kyoto Univ.)
Keywords:
Hydrogen,AZO,thin film
The development of transparent conductive electrodes (TCE) has become more important and critical ascribed to its versatile applications, such as touch screens, sensors, and solar cells for renewable energy. Zinc oxide (ZnO) exhibits excellent properties including, for the most part, high conductivity, particularly when doped with aluminum (Al) and converted into Al-doped ZnO (AZO). Recent research suggests a beneficial effect of hydrogen (H) for producing thin films with superior conductivity and transparency, even compared with AZO. In this study, the AZO-TCE thin films were prepared via the rf-magnetron sputtering technique, with two different sputtering gases, argon (Ar), and NOXAL (95% argon + 5% hydrogen). The crystallographic orientation (texture), electrical, and optical properties were then investigated, where the presence of hydrogen during sputtering and annealing was found to have a significant impact on thin film characteristics. The higher crystallinity and stronger texture are exhibited for Ar-sputtered films, indicating that the H atoms restrict the grain growth of columnar structure, hindering ZnO texture development on the glass substrate. The average crystallite size of AZO films deposited in Ar is correspondingly larger than in NOXAL, while after annealing all the samples exhibit similar values. On the other hand, the former films gain less conductivity than the latter, as deposited, the difference of which is, however, almost eliminated via post-annealing, leading to high conductivity for both. A significant blue shift of the optical absorption edge is exhibited by post-annealing as well, which greatly enhances band gaps for both. A detailed comparison involving H-doping and post-annealing will be presented.