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

Core–shell structured ZnO/SiOx nanowires were synthesized on gold coated silicon(100) substrate by zinc powder evaporation at 550 °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 SiOx amorphous layer and interestingly, the ZnO core was grown along a unique direction of [2 0 2¯ 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.