The growth of ZnO nano-wire by a thermal evaporation method with very small amount of oxygen

Formation of ZnO nano-wire by a thermal evaporation method was studied in this work. The ZnO nano-wire has grown from metal Zn granule under O2 environments at high temperature. We investigated the behavior of the ZnO nano-wire growth with the change of oxygen content in carrier gas (N2). Zn granules were placed in an alumina boat. The boat was inserted in a horizontal tube furnace. The furnace temperature was maintained in the range of 700–1000 °C for 0.5–2 h. The oxygen contents were adjusted from 0.5 to 5 vol% by mass flow controller. The as-grown ZnO nano-wires were characterized by scanning electron microscope (SEM). ZnO nano-wire grew only at 1.6–2.0 vol% O2 conditions. ZnO nano-wire did not grow when the oxygen content is either 0 vol% or higher than 2.5 vol%. From these results, it was confirmed that oxygen content in the thermal evaporation method is an important factor for the synthesis of the ZnO nano-wire.