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 C. Each nanostructure has four arms which are about 3–10 m in length and 0.2–1.5 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.