  Ratio of the intensity of D- Raman peak and G- Raman peak (ID/IG) is often
used for characterization of diamond-like carbon films, for example to estimate
number and size of the sp2 clusters. In this paper we investigate how the
interference effects in the film influence this ratio. It is shown that for
films on silicon substrates the distortion of the real ratio can reach 10 % and
for films on metals even 40 %. This should be taken into account if some
conclusions are made from the measured ID/IG ratio.
