Low-temperature solution approach toward highly aligned ZnO nanotip arrays

Highly aligned and free-standing ZnO nanotip arrays grown on the ZnO films by soft chemical method are proposed. X-ray diffraction analysis shows that the ZnO nanotips are hexagonal wurtzite structure, and the c-axes of nanotips are perfectly along the substrate surface normal. HRTEM demonstrates the ZnO nanotip to be a single crystal. Room temperature photoluminescence of the ZnO nanotips has a strong UV emission band at 378 nm. The field emission of ZnO nanotip arrays shows a turn-on field of about 10.8 V/mum at a current density of 0.1 muA/cm and emission current density up to about 1 mA/cm(2) at a bias field of 19.5 V/mum. The mild technique for fabricating ZnO nanotip arrays is believed to open novel possibilities for nanoscale optoelectronic device applications. (C) 2004 Elsevier B.V. All rights reserved.