Direct growth of flower-like ZnO nanostructures on porous silicon substrate using a facile low-temperature technique

Abstract

Flower-like zinc oxide (ZnO) nanostructures were successfully grown on seed layer-free porous silicon (PSi) substrate using a facile, efficient, and low-temperature technique. An electrical behavior was studied using an electrochemical impedance spectroscopy. Field emission scanning electron microscopy results showed that rough nanoporous surface play an important role in the formation of ZnO flower-like nanostructures. The strong intensity and narrow width of X-ray diffraction peaks indicated good crystallinity of the as-grown ZnO nanostructures. Data from photoluminescence measurements showed a UV band-edge emission with a peak at about 381nm accompanied by a larger and broader visible emission in a 500–800nm wavelength range that indicated the presence of high structural defect levels. The large value of interfacial charge transfer resistance observed in the ZnO/PSi nanostructures (2.25MΩ) can be attributed to the formation of an oxide layer on the Psi surface that possessed a smaller resistance (0.982MΩ). The present flower-like ZnO/PSi nanostructures are envisaged to have promising applications in novel nanoscale chemical solution sensors.