Incorporation of O2 with Ag/AgOx nanocomposite thin films

Abstract

The effect of annealing temperature and time at oxygen atmosphere were detected for Ag films deposited by inert gas condensation (IGC) technique from Ag2O ingot source. Investigation of the resultant Ag/AgOx nanocomposite thin films and its incorporation with oxygen were discussed. The structure of deposited films was determined by both grazing incident in plan X-ray diffraction (GIIXD) and high resolution transmission electron microscope (HRTEM). GIIXD patterns showed only the lines of Ag nanocrystalline cubic structure with the probability of acquiring the AgOx amorphous oxide phase with estimated particle size ranging from 7.96 to 22.2 nm. The HRTEM diffraction patterns indicated that the crystallinity decreased by increasing the annealing temperature and time in oxygen atmosphere. The HRTEM images revealed the surface morphology of crystalline particles at films annealed at 373, 473 K for 2 h and low crystallinity for films annealed at 523 K for 2 h and 5 h. The energy dispersive X-ray analysis (EDAX) data revealed the increase of oxygen percentage in Ag/AgOx nanocomposite films by increasing the annealing temperature and time. Observed aggregations on the films surfaces increased in size as annealing temperature and time increased as seen by field emission scanning electron microscope (FESEM) images. The electrical resistivity of annealed films in O2 atmosphere showed abrupt increase at temperature of 450 K for deposited films followed by gradual decrease. The activation energy Ea has the values of 0.86 and 0.88 eV as the annealing temperature increases from 473 to 523 K for 2 h when heated in vacuum. The optical properties showed change in its behavior from metallic to semiconductor for annealed films at temperatures ≥473 K. The optical band gap due to direct transition have values in the range of 0.94–1.29 eV for film of thickness 55 nm and 1.42 eV for films of thickness 25 nm. The photoluminescence PL spectra showed for all films under study the lines of silver only at ∼400 nm.