title: Catalyst-free direct vapor-phase growth of Zn1-xCuxO micro-cross structures and their optical properties.
abstract: 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.
authors: Laboratory of Condensed Matter Spectroscopy and Opto-Electronic Physics, Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China. wzshen@sjtu.edu.cn.
authors: Danhua
authors: D
authors: Xu
authors: Donghua
authors: D
authors: Fan
authors: Wenzhong
authors: W
authors: Shen