The influence of annealing on structural and photoluminescence properties of silicon-rich Al2O3 films prepared by co-sputtering

Si-rich Al2O3 films were produced by RF magnetron co-sputtering of pure silicon and alumina targets onto a long silicon oxide substrate. The effect of an annealing treatment on structure and light emission property of the films with different Si content was investigated by means of X-ray diffraction, Raman scattering and photoluminescence (PL) methods. The formation of amorphous Si clusters upon deposition process was observed for the films with Si volume content exceeded 70%. The annealing treatment of the films with Si content exceeded 80% results in the formation of Si crystallites with the mean size of about ∼14 nm. Three overlapped PL bands were detected in the 500–950 nm spectral range. The analysis of PL spectrum shape revealed that the near-infrared PL component, peaked at 850 nm, is caused by the exciton recombination inside Si crystallites. Another, the most intense PL band with maximum at 560–580 nm can be ascribed to defects in matrix located near nanocrystal/matrix interface, while the origin of the third PL band with the peak position at 700–750 nm is supposed to be also due to host defects whose nature requires more investigation.