Raman Scattering Studies of Ar+ Implanted CdS Films Prepared by Vacuum Evaporation

CdS thin films were prepared by vacuum evaporation onto glass substrates at room temperature. X-ray diffraction and TEM studies revealed that the as-deposited CdS thin films have a wurtzite (hexagonal) structure, and have been grown with preferential (0002) orientation. The Raman peak of the as-deposited CdS thin film appeared at 303.12 cm—1 with a full width at half maximum (FWHM) of 8.3 cm—1. These films were implanted with a mass analyzed beam of 100 keV Ar+ ions to various doses in the range of 1014 to 1016 ions/cm2. Contrary to the expected reduction in the Raman intensity, there was a monotonic increase in the intensity of the Raman peak with implantation dose. The Raman peak position of the CdS A1(LO) mode did not change much whereas the full width at half maximum (FWHM) was found to increase with implantation dose. These results are explained on the basis of the implantation induced surface roughness and lattice disorder.