Effect of Cu-doping on the photoluminescence and photoconductivity of template synthesized CdS nanowires

Cu-doped CdS nanowires were synthesized within the pores of anodic alumina membrane as template via electrochemical deposition. Morphological, structural, optical and photoconductive properties of the synthesized nanowires were studied. Morphological and structural properties were studied by using SEM with EDS (point & line mapper mode) and X-Ray Diffractometer. Scanning electron microscopy with point EDS and line EDS mapping confirms the deposition of pure CdS and Cu-doped CdS throughout the template length respectively. XRD investigations shows the presence of polycrystalline phase and cubic structure of pristine CdS nanowires. Optical properties were studied by UV-visible absorption spectroscopy and time resolved photoluminescence. A gradual decrease in energy band gap from 2.38 eV to 2.10 eV is observed for Cu doped CdS nanowires. Time resolved photoluminescence studies shows the red shift in emission wavelength and increase of excited state lifetimes with Cu doping and also with increase in its concentration in CdS nanowires. Current-voltage characteristics of pure and doped CdS nanowires studied at varying incident light intensity show that the Cu doped nanowires show negative photoconductivity.