Luminescence properties of tetrapod ZnO nanostructures

The tetrapod ZnO nanostructures are synthesized on the Si (100) substrates using the chemical vapor deposition (CVD) method at 1000℃. Each nanostructure has four arms which are about 3-10 μ m in length and 0.2-1.5 μ m in diameter. Further analyses on structure demonstrate that the tetrapod ZnO nanostructures have single crystalline wurtzite hexagonal structure preferentially oriented in c -axis. The photoluminescence (PL) measurements of the tetrapod ZnO nanostructures revealed a UV peak at 382 nm corresponding to the free exciton emission, and a green peak at 523 nm arising from deep level emission. For comparative analysis, cathodoluminescence (CL) spectra obtained from different regions of an individual tetrapod are investigated. Moreover, a possible growth mechanism of the tetrapod ZnO nanostructures is also discussed based on the experimental results.