Large-scale synthesis, microstructure and growth mechanism of self-assembled core-shell ZnO/SiOx nanowires

Core-shell structured ZnO/SiO, nanowires were synthesized on gold coated silicon(100) substrate by zinc powder evaporation at 550 degrees C. SEM image showed the nanowires were obtained in large-scale. The diameters and the lengths of the nanowires are about 50 nm and several micrometers respectively. XRD, TEM and EDX investigations confirmed the core-shell structure, i.e. the core zone is single crystalline ZnO and the shell zone is SiO chi amorphous layer and interestingly, the ZnO core was grown along a unique direction of [2 0 (2) over bar 1]. A possible mechanism was also proposed. Firstly, gold film served as catalyst and the nanowires grew out from the surface of Au-Si-Zn liquid alloys; secondly, tin powders were used as inhibitor to keep a low partial pressure of zinc vapor. (c) 2005 Elsevier B.V. All rights reserved.