Raman investigations of the surface modes of the crystallites in CdS thin films grown by pulsed laser and thermal evaporation

CdS films have been grown on Corning glass by pulsed laser evaporation (PLE) and thermal evaporation (TE) techniques at a substrate temperature between room temperature and 250 °C. The quality of these films is investigated by resonance Raman scattering, x-ray diffraction and optical transmittance. Our results reveal that the Raman shifts of the surface phonon mode are observed with 300 and 297 cm−1 by PLE and TE techniques, respectively, and as many as four overtones are obtained by PLE method. The difference of Raman shift between these two techniques are caused by the discrepancy of crystallite sizes which is larger for PLE technique. The crystallite sizes are in the range of 200–500 Å in diameter. Highly oriented films have been grown by both of the techniques even when the substrate is at room temperature.