An insight of physical and antibacterial properties of Au-doped ZnO dip coated thin films

Abstract

Undoped and Au-doped ZnO thin films were dip coated on crown glass substrates by sol-gel process technique. The role of Au (1–5 at. wt.%) on structural, magnetic, morphological, dielectric, antibacterial and optical properties of the ZnO films were studied. XRD results depict that all films have a hexagonal wurtzite structure of ZnO and are a-axis oriented. The crystallite size thin films are decreased with an increase in Au doping percentage. Optical properties also confirmed that the s crystallinity degraded with the increase in Au percentage. UV–VIS–NIR optical spectra show that the increase in Au doping into ZnO lattice promotes their transparency. Surface morphology and surface roughness are modified by the Au doping concentration. Magnetic measurement exhibited room temperature ferromagnetic ordering in undoped and Au doped ZnO thin films. The enhancement in saturation magnetization with increase in Au doping is due to creation of defects in ZnO lattice by Au doping due to oxygen vacancies and structural inhomogeneity which leads to development of bound magnetic polarons. Variation in AC conductivity with change in Au dopant percentage is studied using Jonscher's power law which is linked with barrier-hopping mechanism. Au doped ZnO is effective against gram positive and gram-negative bacteria. These have antimicrobial applications in biomedicine and environmental shield. Au doped ZnO thin films are beneficial in spin LEDs and switchable diodes. The Au doped ZnO photocatalyst can efficiently degrade methylene blue dye; hence, it can be used for the treatment of wastewater contamination.