The effects of pulse injection method on the photoluminescence of ZnO nanotetrapods

The ZnO nanotretapods prepared by a catalyst-free thermal oxidation between zinc vapor and oxygen were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). To improve the gas-mixing in the reactor, nitrogen gas was supplied in pulse into the reaction zone. This method could affect the oxygen vacancy within the crystal as well as the photoluminescence spectra of the ZnO nanotetrapods. The effects of pulse injection in term of pulse pressure and pulse period were investigated. The increased flowing period of the supplied nitrogen and the increased pulse pressure resulted in the increase in the oxygen vacancy and visible PL intensity of the product. The pulse of carrier gas with 8 s flowing period and 3 s non-flowing period at 3 bar of pulse pressure brought about the product with the highest oxygen vacancy and visible PL intensity.