Preparation And Characterization Of Au/SiO₂ Nanocomposite Films And SiO₂ Nanowires

Nanomaterials attract more and more attention due to their importance to the study of size- and dimensionality-dependent chemical and physical properties and great potential for nanoscale electronics and optoelectronics. In contrast to the widely application of SiO2 which is the most important photoluminescence materials in the electronic industry, physical properties and mechanism of nanocomposite films and nanowires growth remains less explored.This research mainly includes two aspects, firstly we used the magnetron sputtering technology to sputtering SiO2 layers and Au layers on Si substrates. Au/SiO2 nanocomposite films were fabricated by annealing the deposited substrates in N2. Besides, we fabricate the SiO2 nanowires by sputtering Au onto the Si substrate and annealing with Si powder in N2. We tested and studied the structures, compositions and morphologies by many kinds of electronic microscopes such as SEM, TEM, PL, AFM, XRD, and XPS.We carried the discussion on the nanocomposite films'growth mechanism and the affections of annealing time to the films'morphology, nanostructures and properties. We also discussed the affections of annealing time to the nanowires and growth mechanism of nanowires. The primary contents are as follows:1. Au/SiO2 nanocomposite films were fabricated by magnetron sputtering technology. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) were used to characterize the films'morphology and nanostructures. It is found that the crystallization of Au in the nanocomposite films is very good and the Au crystallites increases with increasing annealing time.2. Au thin film was deposited on the substrates by magnetron sputtering technology. SiO2 nanowires were fabricated by annealing the substrates with Au layer and Si powder. The morphology and compositions of the nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).3. The luminescent behavior of the nanocomposite films was characterized by photoluminescence (PL) with different excitation wavelengths. Ii is found that the emission peak at around 525 nm becomes more and more dominant with annealing time increases. The decrease in the 560 nm emission intensity with annealing time may be ascribed to the diffusion and evaporation of Au. An intensive emission peak at around 325 nm was observed, which is related to the defective structure of the amorphous SiO2 layer because of oxygen deficiency.4. The growth process of the SiO2 nanowires was discussed. Particles were observed at the tip of the SiO2 nanowires, which is consistent with the well-known vapor-liquid-solid (VLS) process. Si powder provides the source of Si vapor at high annealing temperature. The nanowires became curve in the growth process, which is related to the facts of thermal fluctuation etc.