Synthesis and characterization of undoped and copper-doped zinc oxide nanowires for optoelectronic and solar cells applications

This work concentrated on the synthesis of undoped and Cu-doped ZnO nanowires (NWs) by vapor transport method as well as on their physical and chemical characterizations. All X-ray diffraction patterns were indexed to ZnO single phase of hexagonal structure, and no Cu or Cu compounds characteristic peaks were observed. The evaluated Cu at.% was proportional with Cu ratios used in the source alloys. NWs morphology with quite long and smooth surfaces was observed for undoped sample, whereas NWs with agglomerations of particles were observed for higher Cu-doped samples. The overall transmittance decreased with increasing Cu doping ratio with a red shift for the onset of absorption. The optical energy gap was decreased from 3.33 to 3.10 eV upon increasing the Cu ratio from 0 to 5 at.%. Two emission bands were observed in the photoluminescent spectra at 385 and 545 nm, and they …