Improvement of the uniformity of structural and electrical properties of transparent conductive Al-doped ZnO thin films by inductively coupled plasma-assisted radio frequency magnetron sputtering

Abstract

Transparent conductive Al-doped Zinc oxide thin films were deposited on glass substrates by conventional radio frequency magnetron sputtering (C-RFMS) and inductively coupled plasma-assisted radio frequency magnetron sputtering (ICP-RFMS) methods. The structural and electrical properties of films were studied as a function of the radial position (r) of the substrate in both methods. A good thickness uniformity was obtained in ICP-RFMS, while a significant decrease in film thickness was observed at r=30mm (erosion zone) in C-RFMS. The c-axis orientation was achieved in all positions in ICP-RFMS, while crystallinity was degraded at r≥25mm in C-RFMS. Low resistivity ρ of the order of 10−4Ωcm was obtained at all positions in ICP-RFMS, while ρ was rapidly increased at r≥30mm in C-RFMS. In ICP-RFMS, high-energy ion bombardment is suppressed due to the modified plasma density profile and lower space potential. As for transparency, the sample prepared at r=0mm in ICP-RFMS showed an average visible transmittance of 81%, higher than that in C-RFMS. Throughout the study, it was demonstrated that ICP-RFMS method was promising to improve the radial distribution of structural, electrical, and optical properties of Al-doped ZnO thin films.