Surface metalization on the photo-emission, photo-absorption and core-level shift of nanosolid silicon

Cu, Al, and Ti films of ∼ 10 nm thickness were deposited on porous silicon (PS) at room temperature using Filtered Cathodic Vacuum Arc system and annealed at 800°C for 10 min in vacuum. The PS layers were obtained by anodization of Si wafer. X-ray photoelectron spectroscopy, photoluminescence (PL), photo-absorption (PA), and X-ray diffraction studies revealed that before annealing just Cu-deposited sample exhibited PL blueshift, PA redshift, and Si-2p level shift due to the Cu diffusion at the surface of PS. While after annealing, Cu- and Ti-deposited samples exhibited obvious PA redshift and Si-2p level shift, which arise from the crystal field variation due to the formation of Cu/Ti silicides at the surface as well as the conduction electronic transportation.