Cu-Doped ZnO Nanoneedles and Nanonails: Morphological Evolution and Physical Properties

• Published in: Journal of physical chemistry. C 2008-07, Vol.112 (26), p.9579-9585
• Main Authors: Zhang, Zhou, Yi, Jia Bao, Ding, Jun, Wong, Lai Mun, Seng, Hwee Leng, Wang, Shi Jie, Tao, Jun Guang, Li, Gong Ping, Xing, Guo Zhong, Sum, Tze Chien, Alfred Huan, Cheng Hon, Wu, Tom
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp710837h

Controlling novel morphologies and developing effective doping strategies are two important tasks for advancing ZnO-based nanomaterials. We have grown vertically aligned Cu-doped ZnO nanonails and nanoneedles and observed a continuous evolution between various morphologies. Selecting source compositions and regulating vapor and gas pressures modify the Ehrlich−Schwoebel energy barrier for the surface diffusion and determine the morphologies. X-ray diffraction study indicates a decrease in the lattice parameter after the Cu doping. Photoluminescence measurements taken on both doped and undoped samples show that, in the Cu-doped ZnO nanostructures, the band-edge UV emission and the broad green emission are red-shifted by ∼7 and 20 nm, respectively. X-ray photoelectron spectroscopy study revealed a higher level of oxygen vacancies in nanoneedles, which was found to enhance the green emission. Room-temperature ferromagnetism was also observed in Cu-doped ZnO nanomaterials. On the basis of the strong correlations between structures and properties, we demonstrate that the morphologies and the optical and magnetic characteristics can be tailored to a large degree in transition-metal-doped ZnO nanostructures.