Catalytic growth and characterization of ZnO nano-needles

Abstract

Absfrnct-ZnO nanostructures were synthesized at 5W°C over nickel catalyst supported on Si substrate in a homemade vertical chemical vapor deposition (CVD) reactor. The Z n O nanostructures had a needle-like morphology that the diameter of structures decreased linearly from the bottom to the top. The diameters of the Z n O nano-needles normally ranged from 20-100 nm and the lengths were in the range of 2-3 pm. The nanoneedles had a single wurtzite structure. The clear lattice fringes in HRTEM image also revealed the growth of good quality hexagonal single-crystal ZnO. The photoluminescence (PL) spectra of the nano-needles excited with a ultra-violet (UV) emission of 3.3 eV and a weak green emission at 2.4 eV at room temperature. Field emission characteristics of the ZnO nanowires showed that the turn-on field of ZnO nanowires was -6.10 V/pm with a lield enhancing factor p of -1099. The catalytic growth mechanism of the ZnO nanowires was discussed on the basis of experimental results in this work.

CATALYST–FREE GROWTH OF WELL–ALIGNED ZnO NANOWIRES ON GRAPHENE/Si SUBSTRATEBY THERMAL EVAPORATION

“…In our prepared ZnO NWs, a sharp and strong band in the UV region at 380 nm anda weak broad green band peaking at around 516 nm. Comparable results were reported in the literatures [8,33]. The UV emission is well-known as near-band-edge (NBE) emission of the wide band gap ZnO, which originated from a recombination of free-excitons through an exiciton-exiciton collision process [14,19].…”