Atomic layer deposition of palladium coated TiO 2 /Si nanopillars: ToF-SIMS, AES and XPS characterization study

Nanocomposite based on Palladium (Pd) Coated TiO 2 /Si nanopillars is an attractive candidate for photocatalytic applications because of its outstanding electrochemical and optical characteristics. In this research, Pd/TiO 2 /Si nanopillars were synthesized by combination of metal-assisted chemical etching and atomic layer deposition, and then the surface was investigated by means of Electron microscopy, Time-of-Flight Secondary Ion Mass-Spectrometry (ToF-SIMS), Auger Electron Spectroscopy (AES) and X-Ray Photoelectron spectroscopy (XPS). The spatial distribution of different chemical components and contaminations on the surface of the produced nanocomposites was evaluated by ToF-SIMS mapping. Depth profiling by AES was carried out to determine the chemical composition and the conformality of Pd and TiO 2 layer over the Si pillars. The elemental composition and stoichiometry were determined by XPS analysis. The XPS valence band analysis was performed in order to investigate the modification of TiO 2 /Si nanopillars electronic structure after Pd deposition. It was found that the Pd coating decreases the concentration of photoactive defects that can reduce the photoelectrochemical efficiency of TiO 2.