Optoelectronic properties correlation to preparation of Au/La-oxide nanocomposite films

Abstract

Gold nanoparticles were grown in La-oxide thin films deposited on quartz and silicon substrates. These films were annealed in pure hydrogen gas atmosphere at 300?C for different durations 15 min, 30 min, and 45 min and characterised by the X-ray fluorescence (XRF) and X-ray diffraction. The matrix La-oxide remained amorphous up to 400?C. The fraction of Au in La-oxide host material was 7 % molar with crystallite size of 6.8 nm. The Au NPs slightly grew by annealing in H2 gas at 300 K. The samples were investigated by UV-Vis-NIR absorption spectroscopy and dc-electrical measurements. They exhibit conducting properties and with H2 gas annealing, they showed red shifting of the bandgap with remarkable reduction of optical absorption coefficient by ~25 % and remarkable increase in electrical conductivity ~124 %. A global study of the influence of low-temperature post annealing in H2 gas on the electrical, structural, optical, and optoelectronic properties was conducted.