Abstract
In this study, 40 nm nanoparticles of zinc oxide (ZnO) were used to prepare high-density ZnO discs. High-oxygen thermal annealing was found to have a significant effect on ZnO discs, especially in terms of grain growth enhancement. Moreover, unique secondary growth and multilayer grain growth of ZnO nanoparticles were observed. The strong solid state reaction during annealing was attributed to the high surface area of the ZnO nanoparticles, which promoted a strong surface reaction. The ZnO discs were found to contain an extremely high concentration of structural defects, as indicated by the dominant and broad visible photoluminescence emission. Furthermore, this visible emission was significantly increased after annealing treatment. Annealing treatment also improved grain crystallinity, as illustrated by the reduction of intrinsic compressive stress based on the X-ray diffraction lattice constant and full width at half maximum data. Electrical properties were also influenced by annealing treatment, with a marked drop in the breakdown voltage from 240 V (as-grown sample) to 140 V (800 A degrees C sample). Resistivity also exhibited a dramatic drop from 240.2 k Omega cm (as-grown sample) to 72.26 k Omega cm (800 A degrees C sample). Therefore, high-oxygen thermal annealing can be employed as a new technique for controlling the breakdown voltage of ZnO nanoparticle discs with improved structural properties.