Growth and electron field-emission of single-crystalline ZnO nanowires

ZnO nanowires with high density are grown over zinc foil by thermal evaporation process at relatively low temperature. Electron microscopy studies confirmed that the as-grown nanowires are of single crystal hexagonal wurtzite structure, growing preferentially in the c-axis direction. The Raman spectrum of the ZnO nanowires shows an optical-phonon E2 mode at 440 cm−1 confirming good crystallinity for the grown nanowires. The field emission measurement indicated that ZnO nanowires have a turn-on field of 9.1 V/μm at current density of 0.001 μA/cm2.

► The annealing of the Zn foil gives optimum growth of nanowires (NWs) and very thin. ► The ZnO NWs grown on the Zn foil substrate are under compressive stress. ► The turn-on and emission current would be improved by growing well-aligned ZnO NWs array.