Aerosol Assisted Chemical Vapor Deposition of Gold and Nanocomposite Thin Films from Hydrogen Tetrachloroaurate(III)

Hydrogen tetrachloroaurate (HAuCl 4 ) has been investigated as a precursor to gold films using aerosol assisted CVD. [HAuCl 4 ] proved to be an excellent precursor to metallic gold, yielding films under a wide range of conditions with tunable optical properties. In addition, gold particles have been incorporated into several different transition metal oxide thin films (TiO 2, WO 3, and MoO 3 ) using a single step process. The films were deposited onto silica glass using [Ti(O i Pr) 4 ], [W(CO) 6 ], [Mo(CO) 6 ], and [HAuCl 4 ] as precursors, and acetone, methanol, and toluene as solvents. Substrate temperatures from 200 to 400 °C were used. XRD and XPS confirmed the presence of metallic gold and metal oxide within the films. The concentration of gold within the films could be varied widely; the Au:M (M = Ti, W, Mo) atomic ratio ranged from 0.1 to 1.9 depending on the initial precursor ratio. Films showed optical properties characteristic of gold nanocomposite materials: surface plasmon resonance (SPR) absorption peaks and metal-like reflectivity. The frequency and intensity of the SPR absorption was found to be dependent on the concentration of gold particles within the film and the refractive index of the metal oxide matrix.