Check this paper Campbell IH, Fauchet PM. The effects of microcrystal size and shape on the one phonon Raman spectra of crystalline semiconductors. Solid State Commun 1986;58:739–41.
The model defines the Raman intensity I. Using this, you can extract the size of crystallites (r) from corresponding TO modes. I know this has been done for Si,.Ge and GaAs. For examample, for Si-Si TO mode has a peak at 520 cm-1 so having a fit to that peak using richter's model (this model is given in abovementioned paper for several structures, spheres, wires, and films).
Raman signal intensity decrease after hybrid nano structure means their is some change with respect to morphological parameter and chemical changes. I think you analyse this hybrid with PXRD followed electron microscopy for calculate the crystal size................