A high-resolution electron microscopy study of β-SiC nanoparticles formed by C+-implantation of single crystal silicon with subsequent annealing has been carried out. The as-implanted sample had a trilayered structure, in which the surface layer, A, and the bottom layer, C, were crystalline but damaged, and the middle layer, B, was amorphous. After annealing this structure, β-SiC particles were formed throughout the trilayered structure but with different forms: a few epitaxial β-SiC nanoparticles in layers A and C, and more random nanoparticles in layer B. The β-SiC nanoparticles, in the size range 2-8nm, should be responsible for the blue-emitting effect of the silicon-based porous β-SiC