Effects of deposition power and pressure on the crystallinity of Al-doped ZnO thin films at glass substrates by low temperature RF magnetron sputtering

This paper discusses the effects of discharge power and deposition pressure on the structural, electrical and optical properties of Al-doped ZnO (AZO) films deposited at lower substrate temperature by radio-frequency magnetron sputtering. The AZO films have been characterized in detail using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), Hall-effect measurement system and UV-visible spectrophotometer. It was found that the structural, morphological, electrical and optical properties of AZO films are greatly dependent on sputtering pressure and discharge power. The film deposited at 200W, 0.5pa and 100°C exhibited relatively well defined crystallinity and the lowest resistivity of 3.6×10 ^-4ωcm. It was suitable for application as transparent conductive electrodes in solar cells. Meanwhile, the atomic arrangement of AZO film having a wurtzite structure was identified by the experimental and Fourier filtered images as well as electron diffraction. As a result, this paper revealed that the resistivity of AZO film was greatly influenced by the defect density of AZO film.