Catalyst-free direct vapor-phase growth of Zn1−x Cu x O micro-cross structures and their optical properties
1 Laboratory of Condensed Matter Spectroscopy and Opto-Electronic Physics, Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China
2 Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China
3 School of Applied Physics and Materials, Wuyi University, 22 Dong Cheng Village, Jiangmen, 529020, China
Nanoscale Research Letters 2013, 8:46 doi:10.1186/1556-276X-8-46Published: 22 January 2013
We report a simple catalyst-free vapor-phase method to fabricate Zn1−xCuxO micro-cross structures. Through a series of controlled experiments by changing the location of the substrate and reaction time, we have realized the continuous evolution of product morphology from nanorods into brush-like structures and micro-cross structures at different positions, together with the epitaxial growth of branched nanorods from the central stem with the time extended. The growth mechanism of the Zn1−xCuxO micro-cross structures has been proposed to involve the synthesis of Cu/Zn square-like core, surface oxidation, and the secondary growth of nanorod arrays. By the detailed structural analysis of the yielded Zn1−xCuxO samples at different locations, we have shown that the CuO phases were gradually formed in Zn1−xCuxO, which is significant to induce the usual ZnO hexagonal structures changing into four-folded symmetrical hierarchical micro-cross structures. Furthermore, the visible luminescence can be greatly enhanced by the introduction of Cu, and the observed inhomogeneous cathode luminescence in an individual micro-cross structure is caused by the different distributions of Cu.