RAMAN-SCATTERING FROM SP2 CARBON CLUSTERS

Raman spectra of B ion-implanted glassy carbon (GC) and hydrogenated amorphous carbon (a-C:H) films have been measured as a function of polarization direction of the scattered light and excitation wavelength. Raman bands of GC implanted heavily with a fluence of more than 5 X 10(15) B ions/cm2 and a-C:H films show a frequency-independent depolarization ratio, suggesting the existence of sp2 carbon clusters in these samples. It was found that Raman spectra of GC implanted heavily with a fluence of more than 5 X 10(15) B ions/cm2 varied with the excitation wavelength. From a comparative study of the heavily implanted GC and a-C:H films, the variation of the Raman spectra with the excitation wave-length observed for the heavily implanted GC is interpreted in terms of pi-pi* resonant Raman scattering from Sp2 carbon clusters having various sizes.