Formation of ultrathin nanocomposite SiO 2:nc-Au structures by Pulsed Laser Deposition

Abstract

A method for the formation of Au nanocrystal (nc) arrays embedded in an ultrathin SiO 2 layer in one vacuum cycle is proposed. The method is based on the co-deposition in vacuum of ∼1 nm thick uniform Si–Au amorphous layer at a specific composition ratio by Pulsed Laser Deposition on the pre-oxidized Si(1 0 0) substrate, followed by its oxidation in the glow discharge oxygen plasma at room temperature, resulting in the precipitation of Au ncs at the bottom interface and/or at the surface of the forming SiO 2 layer. The capping SiO 2 layer is formed by the glow discharge plasma oxidation of further deposited ultrathin Si layer. Au ncs 2–5 nm in size and with the separation of ∼3–20 nm from each other segregate during the oxidation of Au–Si mixture as evidenced by transmission electron microscopy (TEM). The evolution of Au and Si chemical state upon each step of the SiO 2:nc-Au nanocomposite structure formation is monitored in situ by X-ray photoelectron spectroscopy (XPS). The metrology of nanocomposite SiO 2:nc-Au structures describing the space distribution of Au ncs as a function of Au/Si ratio is presented.