Insight on Photocatalytic and Photoinduced Antimicrobial Properties of ZnO Thin Films Deposited by HiPIMS through Thermal Oxidation

Zinc oxide thin films have been developed through thermal oxidation of Zinc thin films grown by high impulse power magnetron sputtering (HiPIMS). The influence of various sputtering power on thin film structural, morphological, photocatalytic, and antimicrobial properties was investigated. X-ray diffraction (XRD) analysis confirmed that the crystalline phase of ZnO thin films consists of a hexagonal wurtzite structure. Increasing the sputtering power will lead to intrinsic stress on thin films that promote whisker formation. In this study, whiskers were successfully developed on the thin films without precursors/catalysts and not thermally treated over the Zn melting point. This finding showed that the film phase structure and morphology are significantly affected by sputtering power. It was found that ZnO thin films exhibit high photocatalytic performance under UV irradiation (89.91%) of methylene blue after 300 min of irradiation. The antimicrobial activity on ZnO thin films showed significant inhibition activity (p < 0.05) against E. coli, S. aureus, and C. albicans. However, the whisker formation on ZnO thin films is not accessible to enhance photocatalytic and antimicrobial activity. This study demonstrates that the HiPIMS method through the thermal oxidation process can promote a good performance of ZnO thin films as photocatalyst and antimicrobial agents.