Self-assembly of ZnO nanowires and the spatial resolved characterization of their luminescence

The self-assembled growth of ordered ZnO nanowires on GaN/Si layers has been observed at the low temperature of 5 00 degreesC through Zn evaporation and oxidation. The nanowires have a nearly uniform diameter of 40 nm and length of similar to330 nm. No metal catalyst was used. Interestingly, the nanowires grow on a wetting film of an interconnected vortex-like structure. An empirical model is proposed to explain the growth process. Spatially resolved cathodoluminescence (CL) measurements show a sharp and intense emission (18 line) from the nanowires, while weak and redshifted luminescence from the wetting layer. The CL indicates the existence of tensile stress in the wetting layer while the nanowires are fully relaxed.