Enhanced photoluminescence effects in nanostructured cubic CdS matrix doped with Cu2+ obtained by chemical Bath deposition

Abstract

In the present work, we highlight the enhancements of the photoluminescent properties of the binary II-VI nanocomposite thin film semiconductor cadmium sulphide (CdS) doped with the metallic ions Cu2+ obtained by low-temperature chemical bath deposition (CBD). The doping percentage of the CdS matrix was around 1.74% determined by X-ray fluorescence spectroscopy. The most intense photo-electronic transitions of Cd 3d5/2 (404.94 eV), S 2p3/2 (161.52 eV) and Cu 2p3/2 (933.27 eV) were detected by X-ray photoelectron spectroscopy. The crystallographic study shows that the preferential growth planes are cubic (111) both in the matrix and the doped samples. HRTEM micrographs exhibit the reduction of the particle size of the CdS matrix from 5.87 to 4.76 nm in the doped sample, which confirms the quantum confinement effect. The first optical effect of the doped CdS was noticed in Raman spectroscopy by a frequency shift of the first longitudinal optical mode (1LO-CdS) from 306 to 302 cm−1, related with the shrinking of the nanoparticle, also a great improvement in the sensibility of the characterization by the surface effects of the Cu2+ metallic ion. Photoluminescence was measured in the temperature range of 258–298 K, which showed more recombination emissions of energetic excitons as consequence of the decrease in particle size and the defects created by the Cu2+ metallic ion in the doped sample in whole the range of investigated temperatures. Also the pronounced stimulation of the luminescent spectra of the semiconductor compound at room temperature. Keywords: CBD-CdS, Doping copper, Raman spectroscopy, XPS, XRD, Surface effects, Photoluminescence