Electrical and optical properties of Li-doped Ni–Si–O thin films

The Li-doped Ni–Si–O thin films (LixNi0.90−xSi0.10O, x=0.0–0.05) have been prepared by a sol-gel spin-coating method on silicon and quartz glass substrates. Analysis of phase composition and microstructure indicates that the films consist of cubic NiO phase and amorphous phase as annealed at 700°C for 5min. With the Li-doping concentration increasing, the core-level photoemission spectra show that a loss of the double-peak structure of the Ni 2p3∕2 main line can be observed and current density of the films increases greatly, which should be ascribed to the increase of the hole carriers induced by the Li doping. Ultraviolet-visible absorption spectra indicate that the absorption edge of the films exhibits a redshift due to the related defects.