This work reports on the crystallization of alpha-Si3N4, beta-Si3N4, and silicon in plasma enhanced chemical vapour deposition silicon nitride films grown with SiH4 and NH3 at 400 degrees C and annealed at 1150 degrees C. Nanometric multilayer structures, composed of alternating layers of silicon nitride and silicon-rich nitride, were used as the starting material. The final product is a thin-film Si-Si3N4 nanocomposite. The formation of this composite is verified using glancing incidence X-ray diffraction, transmission electron microscopy and Fourier transform infra-red spectroscopy. Annealing investigations indicate that the multilayer structure plays a key role in the formation of this composite and for the relatively low temperature formation of alpha- and beta-Si3N4 nanocrystals. (C) 2008 Elsevier B.V. All rights reserved.