Microstructure and optical absorption properties of Au-dispersed CoO thin films

Au nanoparticles dispersed cobalt monoxide (CoO) composite films were fabricated via a chemical solution approach combined with a spin-coating processing. Au particles were spherical approximately and uniformly dispersed in the amorphous CoO matrix. The mean diameters of Au particles in the Au/CoO thin films with 40 mol% Au are about 30 nm. The optical absorption peaks due to the surface plasmon resonance (SPR) of Au particles were observed in the UV–vis absorption spectra in the wavelength range of 550–650 nm. The SPR peaks exhibit a red shift and intensify with increasing Au content from 10 to 40 mol%, but show a blue shift and weaken from 40 to 60 mol%. The band gap Eg decreases with increasing Au contents from 10 to 40 mol% but increases by further increasing Au content.

► Au/CoO composite films were fabricated via a chemical solution approach.
► An enhanced nonlinear optical absorption property was found in Au/CoO films.
► SPR peaks due to Au particles achieved in the wavelength range of 550–650 nm.
► Au/CoO films increase potential applications in the nonlinear optical field.