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We have adopted two methods, sol–gel and solid-state synthesis methods to show the effect of grain size and the effect of temperature in the conductivity study.

This work is devoted to the synthesis and study of the different properties of ZnO nanoparticles (NPs) doped with the Ni element.

The optical transmission spectra, the photoluminescence (PL), and the photoluminescence excitation (PLE) spectra of the cobalt doped zinc oxide nanorods Zn1−xCoxO (x = 0.01, 0.10) were measured by Loan et al. [J. Phys. D: Appl. Phys. 42, 065412 (2009)] in the region 1.5-4 eV. These spectra exhibit a group of ultraviolet narrow lines in the region of 3.0-3.4 eV related to the near-band-edge emission of the host ZnO materials and a group of emission lines in the red region of 1.8–1.9 eV assigned to the radiative transitions within the tetrahedral Co2+ ions in the ZnO host crystal. The group of lines in the visible region provides important information about the electronic structure of the cobalt doped zinc oxide nanorods. This work investigates a theoretical crystal-field analysis of the visible lines associated to the Co2+ ion transition occupying a Td site symmetry in ZnO host crystal. A satisfactory correlations were obtained between experimental and calculated energy levels. The electronic structure was compared with the reported for cobalt transition ion doped in ZnO nanoparticles and bulk crystals [Volbers et al., Appl. Phys. A 88, 153 (2007) and H. J. Schulz and M. Thiede, Phys. Rev. B 35, 18 (1987)]. In order to explain the existence of excitation peaks observed near the band edge of the ZnO host, an energy transfer mechanism is proposed.

We have studied the photoluminescence emission line at 3.31 eV in ZnO nanowires. In undoped ZnO, this band strongly depends on high oxygen concentration and could originate from recombination of bound-exciton complex related to structural defects. Conversely, in doped ones, the photoluminescence emission appears notably at a low VI/II ratio and with the emergence of donor-acceptor pair emission due to the presence of α-No nitrogen complex, which acts as a shallow acceptor in ZnO. We found that this band corresponds to 3LO, the third phonon replica of resonant Raman scattering. Furthermore, a remarkable variation is detected in a number of resonant Raman scattering multiphonons.

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Wurtzite ZnO thin films were prepared on sapphire substrate by metal organic chemical vapor deposition (MOCVD). Raman scattering studies on different crystallographic textures were performed in the backscattering geometry, and polarization effect is investigated in different configurations z()prefix−prefix−truez¯ and x()prefix−prefix−truex¯. ZnO Raman modes are investigated in each texture. In the case of ZnO thin film deposed on r‐(11‐22) sapphire plane and using backscattering geometry, new Raman line was observed at 390 cm−1 because this mode has not been noticed in this geometry. It is shown that the frequencies of the quasi‐phonon modes of the examined thin film are in good agreement with the theoretical values calculated within the framework of Loudon model. Copyright © 2014 John Wiley & Sons, Ltd.