Modulated growth density of ZnO nanowires using seed-containing composite film

A layer of ZnO nanoparticles was created by converting Zn2+ ions present inside polymer composite film to ZnO phase by heat treatment in air. Formed nanoparticles served as seeds for the subsequent growth of ZnO nanowires by a hydrothermal process. The size and density of nano-seeds could be modulated by simply varying the amount of Zn2+ ion in the polymer film, affecting the areal growth density and morphology of the nanowires. It was found that growth from nano-seeds smaller in diameter resulted in nanowires with a smaller diameter and a lower areal growth density. Furthermore, longer nanowires with a higher aspect ratio were produced by a repeated hydrothermal process and were characterized with respect to the degree of vertical alignment and optical properties.