Dip coating method is used for depositing Aluminium (Al) doped Zinc Oxide (ZnO) thin films on glass substrate. Undoped, 1%, 3% and 5% Al doped ZnO thin films are prepared and their structural, morphological and optical properties are studied. X-ray diffraction study confirms that films are polycrystalline with hexagonal arrangement. Field Emission Scanning Electron Microscope (FESEM) is used to analyze the surface morphology and it shows the spherical like structure. Energy Dispersive X-ray Analysis (EDX) pattern shows the presence of Zn, O and Al. UV-Vis. Spectroscopy and Photoluminescence spectroscopy (PLS) are used to study optical properties. Optical study indicates that both undoped and Aluminium doped ZnO films are transparent in UV region and closer to visible region. The band gaps of the films are 3.55eV, 3.68eV, 3.82eV and 3.25eV for undoped, 1%, 3% and 5% Aluminium doped ZnO films correspondingly.

Zinc oxide (ZnO) thin films were prepared by modified Successive Ionic Layer Adsorption and Reaction (SILAR) method. The optical, structural and antibacterial properties of the prepared ZnO films were analyzed as a function of its annealing temperature lying in the range of 250ºC to 450ºC. Optical properties were studied using UV-Visible spectroscopy and Photoluminescence spectroscopy (PLS). Optical absorption spectra exhibited blue shift when compared to the bulk value and also the presence of interstitial Zn + ion defect and oxygen ion vacancy were confirmed in the prepared ZnO thin films by PL studies. X-Ray Diffraction (XRD) pattern revealed the formation of hexagonal phase ZnO and the intensity of the film were found to increase with increase in annealing temperature. Field Emission Scanning Electron Microscope (FESEM) images show the presence of flower like structure and pinhole free film throughout the substrate. Antibacterial activity against Escherichia coli (E.coli) was highly dependent on the presence of interstitial Zn + ions and for Staphylococcus aureus (S.aureus) it was dependent on oxygen vacancy in the films.

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The present investigation demonstrates the formation of silver nanoparticles by the reduction of the aqueous silver metal ions during exposure to the Lagenaria siceraria leaf extract. The synthesized AgNPs have characterized by UV-visible spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. AgNPs formation has screened by UV-visible spectroscopy through colour conversion due to surface plasma resonance band at 427 nm. X-ray diffraction (XRD) confirmed that the resulting AgNPs are highly crystalline and the structure is face centered cubic (fcc). FT-IR spectrum indicates the presence of different functional groups present in the biomolecules capping the nanoparticles. Further, inhibitory activity of AgNPs and leaf extract were tested against human pathogens like gram-pastive (Staphylococcus aureus, Bacillus subtilis), gram-negative (Escherichia coli and Pseudomonas aeruginosa). The results indicated that the AgNPs showed moderate inhibitory actions against human pathogens than Lagenaria siceraria leaf extract, demonstrating its antimicrobial value against pathogenic diseases.

Thin films of pure zinc oxide (ZnO) and aluminium (Al) doped ZnO were deposited by two step SILAR technique. Pure and Al (1%, 3%, 5%) doped ZnO thin film’s structural, morphology and optical properties were analyzed. Diffraction peaks of all the samples were indexed to hexagonal Wurtizite structure. The crystallite size, lattice parameters, dislocation density and microstrain were calculated for the prepared thin films. Morphology study using FESEM shows spherical shaped structure of pure ZnO and hexagonal faced rod like structure for Al doped ZnO thin films. The UV-vis absorption spectrum for the thin films was also studied. There is decrease in bandgap as the Al doping ratio increases from 1% to 5%. Photoluminescence studies confirmed that oxygen ion vacancy and interstitial Zn+ ion were present. The maximum zone of inhibition was studied against the Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria by agar diffusion method. Significant antimicrobial results were seen in pure and Al doped ZnO. Aluminium doped ZnO shows more antimicrobial activity over pure ZnO.