Growth and characterization of Cu-catalyzed ZnO nanowires

Abstract

Cu-catalyzed ZnO nanowires have been synthesized by thermal evaporation of Cu- Zn powder alloys in a water vapor atmosphere. The diameters of the nanowires can be controlled by the amount of water vapor introduced into in the reaction tube. Raman spectroscopic characterization reveals two additional modes at 621 and 671cm−1 which are indicative of the existence of host-lattice defects caused by Cu doping or other intrinsic lattice defects that formed during the nanowire growth. Field emission and photoluminescence (PL) properties of Cu-catalyzed ZnO nanowires have also been investigated using nanowires with a diameter of 20 nm and 200 nm. The field emission results show that the thinner nanowires have a lower turn-on electrical field than the thicker ones, whilst both nanowires exhibit a similar field emission enhancement factor in the high electric field region. In the PL spectra, we have observed a blue-shift of the UV emission peak and a red-shift of the green emission peak when the nanowire diameters decreased from 200 nm to 20 nm.