We present the Raman spectroscopic characterization of thermally sintered CdTe/CdS-colloids in thin films. From the spectral data one can conclude that the thermal sintering of the CdTe/CdS-films between 100 degrees C and 200 degrees C initiates the CdTe cluster growth. Sintering temperatures of 300-400 degrees C lead to a release of the Tributylphosyhin- (TBP) capping ligands and to the formation of bare CdS- and CdTe nanocrystals. Above 400 degrees C, the CdTe part of the nanostructures sublimates, leaving behind nearly pure CdS nanocrystallites.