Ag/ZnO Nanocomposites Studied by X-ray Photoelectron Spectroscopy

Ag/ZnO nanocomposites were prepared on Si(100) substrates by an innovative approach consisting of the deposition of ZnO host matrices by Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) and the subsequent dispersion of Ag guest particles by Radio Frequency (RF)-sputtering. In particular, ZnO nanostructures were synthesised from Ar-O2 plasmas using a Zn(II) bis(ketoiminate) precursor at 300 °C and 1.0 mbar, with an RF-power of 20 W. Subsequently, Ag was sputtered on the obtained systems under mild conditions (Ar, total pressure=0.3 mbar; substrate temperature=60 °C; RF-power=5 W). The structural, morphological and compositional features of the obtained nanosystems were analysed by Glancing Incidence X-ray Diffraction (GIXRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDXS). To attain a detailed insight into the chemical characteristics of the Ag/ZnO nanocomposites, this contribution is devoted to the investigation of a representative specimen by X-ray Photoelectron (XPS) and X-ray Excited Auger Electron (XEAES) Spectroscopies. In particular, the attention is focused on the analysis of the O 1s, Zn 2p3/2, Zn 3p and Ag 3d core levels, as well as zinc and silver Auger signals. The results highlight an appreciable silver surface oxidation and an electronic interplay between Ag/Ag2O and ZnO phases.