Carbon ions were implanted into crystal silicon wafers at an energy of 50 keV and with a dose of 1017cm−2followed by thermal annealing. A layer of polycrystalline &bgr;‐SiC was formed beneath the sample surface. Porous nanometer structures were prepared by conventional anodization. At room temperature, the samples exhibit a blue luminescence peak at 2.79 eV (445 nm), which is higher than the energy gap of bulk &bgr;‐SiC (2.2 eV), and its intensity is stronger than that of the reference porous silicon. The results could be explained by the quantum confinement effect. ©1995 American Institute of Physics.