Raman study of silicon nanocrystals formed in SiNx films by excimer laser or thermal annealing

Silicon nitride films of different stoichiometric composition were studied using Raman spectroscopy. A Raman signal due to Si–Si, Si–N bond vibrations in silicon nanoclusters was detected in as-deposited films. The appearance of Raman peaks in the range 493–514 cm−1 after thermal and pulse laser treatments was interpreted as formation of silicon nanocrystals with sizes from 1.3 up to 5 nm depending on treatment parameters. Thermal treatment at 1200 °C allowed Si atom diffusion and its gathering in Si nanocrystals, meanwhile 5 ns pulse laser irradiation leads to crystallization of preexisting silicon nanoclusters inside the as-deposited SiNx films.