The composition and structure of crystalline silicon implanted with carbon ions at high dose were studied using spectroscopic ellipsometry. A brief description of our spectroscopic ellipsometer system and the modeling method adopted for the analysis of the data are included. The crystal damage caused by carbon‐ion implantation in the as‐implanted sample was characterized as an amorphous region of atomic or chemical mixture of silicon and carbon atoms. The recrystallization of Si and the formation of crystalline silicon carbide on annealing these specimens at 800 °C and 1000 °C were investigated through similar spectroscopic ellipsometry studies.