Nanostructural and optical features of hydrogenated nanocrystalline silicon films prepared by aluminium-induced crystallization

A 30-nm-thick Al layer was deposited on top of the hydrogenated amorphous silicon films by radio frequency magnetron sputter, and then heat-treatments were carried out at temperatures of 350∼500 °C. The intensity of the photoluminescence spectra of the post-deposition heat-treated films gradually increased at wavelengths of ∼420 as well as ∼580 nm with raising the annealing temperature from 350 to 500 °C. It is highly likely that the observed increase of the photoluminescence intensity is caused by the increase in the total volume of the nanocrystallites with the size of ∼2 and ∼5 nm in the films, respectively. These also indicate that the aluminium-induced crystallization processing enhances the nucleation of Si crystallites in the films, resulting in the decrease of the lowest crystallization temperature from 500 to 350 °C.