Formation Of Ultrathin Nanocomposite Sio_2:nc-au Structures By Pulsed Laser Deposition

摘要

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(100) 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.