Influence of magnetron configurations on the structure and properties of room temperature sputtered ZnO thin films

Abstract

Under the unbalanced magnetron (UBM) sputtering process, not only the plasma is confined near the target like in the conventional balanced magnetron (BM) sputtering process, but also extends towards the substrate and support the ion-assisted deposition (surface of thin films is bombarded by energetic Ar+ ions during the sputtering process). Here, we report the influence of magnetron configurations on the structure and properties of room temperature sputtered ZnO thin films while keeping other process parameters fixed. The UBM configuration has significantly improved various properties of ZnO thin films in comparison to the BM configuration. The crystalline quality with dominant orientation (002) and uniform distribution of grains is observed while an increase in the band gap from 3.25 eV (BM) to 3.33 eV (UBM) is obtained. The lower defects as investigated from Zn2p and O1s core level XPS spectra, which is well supported by Photoluminescence measurements. In addition to that, surface hydrophobicity has been increased from 121.2° (BM) to 125.5° (UBM). Thus, the unbalanced magnetron configuration in the sputtering process significantly enhanced the structural, optical and surface properties of ZnO thin films even at room temperature and low plasma power without any post annealing treatments, which is highly desired for the device fabrication.