In this work we present Raman and transmission electron microscopy (TEM) characterization of high fluence C implanted nanometric silicon on insulator. The analyzed samples were 35 and 60 nm top layers of Si, which were entirely converted into SiC layers by 2.3 x 10(17) cm(-2) and 4.0 x 10(17) cm(-2) carbon implantations. We report the behavior of C-C signal from Raman spectra for such overall Si to SiC conversions before and after 1250 degrees C annealing. A remarkable effect is observed in the region of C signal (1100-1700 cm(-1)), where fitting with Lorentzian curves reveals that there are different types of C-C bonds. Raman spectroscopy in this region was then employed to relatively characterize the SiC structural quality. TEM measurements support our Raman interpretation by direct structural evaluation of the formed SiC layers. (C) 2012 Elsevier B.V. All rights reserved.