ZnO Nanoparticle Thin Film Research Articles

Electrical Bistability in Zinc Oxide Nanoparticle-Polymer Composites

The article reports observed electrical bistability in thin films of ZnO nanoparticles embedded in an insulating polymer matrix. From the current-voltage and impedance characteristics, they studied transport mechanisms involved in the two conducting-states. The electrical bistability in such films has been associated with a memory phenomenon. The bistability, which is reversible in nature, led to read-only and random-access memory applications in the devices based on such nanoparticles.

Optical and electrical properties of ZnO nanoparticle thin films deposited on quartz by sparking process

ZnO nanoparticle thin films were deposited on quartz substrates by a novel sparking deposition which is a simple and cost-effective technique. The sparking off two zinc tips above the substrate was done repeatedly 50–200 times through a high voltage of 10 kV in air at atmospheric pressure. The film deposition rate by sparking process was approximately 1.0 nm/spark. The ZnO thin films were characterized by X-ray diffraction, Raman spectroscopy, UV–vis spectrophotometry, and ionoluminescence at room temperature. The two broad emission peaks centered at 483 nm (green emission) and 650 nm (orange-red emission) were varied after two-step annealing treatments at 400–800 °C. Moreover, the electrical resistivity of the films was likely to be proportional to the peak intensity of the orange-red emission.

Dynamic recovery and optical properties changes in He-implanted ZnO nanoparticles

A study of the effects of ion-implanted He+ on the photoluminescence (PL) of ZnO nanoparticles is presented. This investigation is motivated by the need to further understand the effects of damage resulting from the implantation process on the luminescence response of the nanoparticles. ZnO nanoparticles were synthesized by reacting zinc acetate with lithium hydroxide. The nanoparticle suspension was then dip coated on SiO2 substrates producing thin films of ZnO nanoparticles, which were then implanted with He+ ions at either room temperature or 400°C. Following implantation, the PL spectrum of the ZnO nanoparticles was investigated and compared to that obtained from He-implanted bulk ZnO. Change in the overall luminescence efficiency was found to depend on both the size of the nanoparticles and the implantation temperature, and is attributed to the dynamic recovery of collision cascades in the ZnO nanoparticles. In addition, a comparison of He+-implanted ZnO nanoparticles with He+-implanted ZnO single crystals indicates that the origin of the green luminescence occurring from the ZnO nanoparticles is near-surface complex defects.

Two-photon pumped random laser in nanocrystalline ZnO

Thin film of ZnO nanoparticles with dimension of about 5–10nm were fabricated by the pulsed laser ablation method. By using a femtosecond laser beam at 700nm to pump micrometer-thick films the authors observed two-photon-induced lasing at 385nm. Experimentally obtained dependence of the threshold on the excitation spot radius r0 is closer to (1∕r02) than to (1∕r0), thus suggesting efficiency of the feedback by scattering-random lasing. The experimental data on nonlinear transmission of the film at the wavelength of pumping are presented.