ZnO nanowire arrays with low defect densities were grown electrochemically. The nanowire morphology was significantly changed when ammonium chloride was added to the source material, and an applied potential up to −1.2 V resulted in a homogeneous distribution of the nanowires, while at −1.4 V, inhomogeneous growth was observed. Photoluminescence spectra were excited by both 248 and 325 nm lasers. A lower intensity of defect emission and a blue shift of the band edge emission peak were observed as compared to undoped ZnO. The improved quality is explained in terms of the reduction of oxygen vacancies due to the presence of chlorine. These findings may have potential in fabricating ZnO nanowires with reduced defects at low cost for optical and optoelectronic applications.

Variable temperature photoluminescence of ZnO thin films deposited by a reactive laser ablation of metallic zinc was investigated. Free and bound exciton emissions are absent at cryogenic temperature, and the near band edge (NBE) emission is independent of measurement temperature for the ZnO thin film deposited at room temperature. Annealing at 700 °C results in the removal of defects, reappearance of exciton emission, and a temperature dependent NBE emission. The experimental data suggest that defects play an important role in the band edge emission in terms of both spectra shape and temperature dependence. Our observations will have an impact on device applications using ZnO, especially for optoelectronics that utilizes the exciton emission.

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Highly transparent ZnO thin films were deposited at different substrate temperatures by pulsed laser deposition in an oxygen atmosphere. The thin films were characterized by various techniques including X-ray diffraction, scanning electron microscopy, optical absorption, and photoluminescence. We demonstrated that oriented wurtzite ZnO thin films could be deposited at room temperature using a high purity zinc target. Variable temperature photoluminescence revealed new characteristics in the band edge emission. The underlying mechanism for the observed phenomena was also discussed.thin films, pulsed laser deposition, optical property, zinc oxide

ZnO thin films were grown using pulsed laser deposition by ablating a Zn target in various mixtures of O2 and N2. The presence of N2 during deposition was found to affect the growth of the ZnO thin films and their optical properties. Small N2 concentrations during growth led to strong acceptor-related photoluminescence (PL), while larger concentrations affected both the intensity and temperature dependence of the emission peaks. In addition, the PL properties of the annealed ZnO thin films are associated with the N2 concentration during their growth. The possible role of nitrogen in ZnO growth and annealing is discussed.