Control of ZnO nanowire growth and optical properties in a vapor deposition process

A vapor deposition method was applied to synthesize zinc oxide (ZnO) nanowires and nanorods with diameter from 40 nm to 500 nm, length from 1 μm to 70 μm by adjusting the flow rate of argon, oxygen and the pressure during growth. Results of scanning electron microscopy (SEM) and high resolution transmission electron microscopy (TEM) proved the hexagonal wurtzite structure of the synthesized ZnO nanowires or nanorods, which grow along the <0001> direction. The results show that the growth conditions strongly impact the morphology, growth rate and optical properties of the ZnO nanostructures. The ZnO nanowires with small diameters tend to show stronger ultraviolet (UV) light emission from the electron-hole recombination near band edge in photoluminescence (PL), while those with larger diameters tend to exhibit PL spectra dominated by the broad green light emission due to the defects.