A method for the formation of Au nanocrystal (nc) arrays embedded in an ultrathin SiO2 layer in one vacuum cycle is proposed. The method is based on the co-deposition in vacuum of similar to 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 SiO2 layer. The capping SiO2 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 similar to 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 SiO2: nc-Au nanocomposite structure formation is monitored in situ by X-ray photoelectron spectroscopy (XPS). The metrology of nanocomposite SiO2: nc-Au structures describing the space distribution of Au ncs as a function of Au/Si ratio is presented. (C) 2008 Elsevier B. V. All rights reserved.