Photoluminescence and Raman scattering of ZnO nanorods

Zinc oxide (ZnO) nanorods were synthesized by a simple microemulsion method. The photoluminescence (PL) spectra at room temperature were measured. The strong UV excitonic emission indicates the good optical properties, and the weak deep-level emission reveals very limited structural defects in the crystals. The multiple peaks in the PL spectrum obtained at 15 K are assigned to the donor-bound exciton (DBE), free to bound transition (FB) and FB–LO phonon replicas. The temperature dependence of energy, intensity, and linewidth of each emission band confirms the effect of thermal ionization progress of excitons and nonradiative recombination activated thermally. The nonresonant Raman scattering spectra at room temperature were excited by He–Ne laser (wavelength ∼632.8 nm). The perfect wurtzite structure in ZnO nanorods has been verified by the intense E2 modes, which include low and high frequency vibrations. The possible reasons for the red shift and broadening of vibration modes were studied by the resonant Raman scattering spectra at room temperature. The power-dependence of Raman shift and FWHM shows the laser irradiation effect on the vibrational modes.

Graphical abstractZinc oxide (ZnO) nanorods were prepared by a simple microemulsion method. The strong UV exciton emission indicates good optical property and weak deep-level emission reveals very limited structural defects in the crystals. We assign the multiple peaks in PL spectrum obtained at 15 K to donor-bound exciton (DBE), free to bound transition (FB) and its LO phonon replicas. The nonresonant Raman scattering spectra at room temperature are excited by He–Ne laser (wavelength & sim;632.8 nm). The intense E2 modes, which include of low and high frequency vibrations, approve the perfect wurtzite structure in ZnO nanorods. Through the resonant Raman scattering spectra at room temperature, the possible reason of vibration modes redshifting and broadening was studied. The power-dependence of Raman shift and FWHM shows the laser irradiation effect on the vibrational modes.Figure optionsDownload full-size imageDownload as PowerPoint slide