Nanostructural, Optical, and Chemical Features of Al-Added Nanocrystalline-Si Thin Films

The nanostructural and optical features of Al-added nanocrystalline Si (nc-Si) thin films, which were prepared by co-sputtering Al-chips and a Si main target, were investigated in terms of Al-addition and post-deposition annealing conditions; the optical features like photoluminescence (PL) and electroluminescence (EL) were related with the variation in the nanostructure of the films. The PL intensity as well as the relative volume fraction of Si nanocrystallites increased with increasing the concentration of Al to a certain level. In particular, the PL spectra of the films which were prepared with 4 Al-chips and then annealed at 800 °C for 60 min exhibit a significant increase in intensity at a wavelength of ∼620 nm, compared to those of the films prepared without Al-addition. It is highly likely that the observed increase in the PL intensity is caused by the raise in the total volume fraction of the ∼3.0 nm-sized nanocrystallites in the films. It was found that the addition of Al as well as the post-deposition annealing can allow adjustment and control of the nanostructural and light-emission features of the nc-Si films.