Growth of ZnO microcrystals from Zn and Cu chloride precursors

The study of the growth mechanism of ZnO microcrystals at relatively low (∼ 300 ℃) temperatures using ZnCl₂ and CuCl vapor showed that at 230 ℃ the powdery layer of zinc and copper chloride particles was formed on Si substrate. In the local places of a layer the CuCl vapor produced the eutectic compositions with ZnCl₂, which have a low melting point of 241 ℃. As the substrate temperature exceeded that value, the eutectic compositions melted forming liquid droplets. The molten droplets were actively absorbing the ZnO vapor. Their oversaturation resulted in the precipitation of solid ZnO nuclei. The further growth of ZnO microcrystals proceeded through the Vapor-Solid mechanism forming rod-like crystals at 290 ℃, or elongated, one-dimensional ZnO structures at 330 ℃. (author)