Simultaneous Enhancement of Transparent and Antibacterial Properties of ZnO Films by Suitable F Doping

Undoped and fluorine doped ZnO (ZnO:F) thin films were deposited onto glass substrates by employing a simplified spray pyrolysis technique using a perfume atomizer. The fluorine doping level in the starting solution was varied from 0 to 20 at.% in steps of 5 at.% and the effects of fluorine doping level on the structural, optical, surface morphological properties along with their antibacterial activity against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria were studied and reported. The X-ray diffraction studies revealed that despite the orientation of crystallites was strongly influenced by fluorine doping, the preferential orientation was retained in favor of (002) plane even at the highest doping level. The crystallite size decreased as the F doping level was increased and the reason for this variation has been explained on the basis of Zener pinning effect. The average optical transparency in the visible range was about 80%-90% for doped films and the optical band gap was found to be slightly increased with the F doping level. The antibacterial efficiency of the F doped ZnO films was found to be enhanced as the F doping level was increased. The antibacterial efficiency was more pronounced in the case of B. subtilis (Gram-positive) when compared with E. coli (Gram-negative).