Modification of spectroscopic properties of nanostructured CdS thin films by Cu+ ion implantation

Nanostructured CdS thin films synthesized by chemical bath deposition method were implanted with Cu+ ions at the doses of 5×1014, 1×1015 and 5×1015 ions/cm2. The grain size of the as-prepared samples as observed from the HRTEM images was ∼6 nm. The UV-Visible absorption and Raman spectra of as-prepared and Cu+ ion implanted samples were recorded. The optical absorption spectrum of the as-prepared sample showed a blue shift in the absorption edge indicating quantum confinement effect. The band gap value of the Cu+ ion implanted samples was found to be decreasing with increase in implantation dose. Raman peak appearing at 300 cm−1 for both as-deposited and Cu+ ion implanted samples was attributed to A1 (LO) phonon of CdS, and the peak that appeared at 230 cm−1 in the case of Cu+ ion implanted samples was interpreted as E1 (TO) mode resulting from the lattice disorder created due to ion implantation.