Open Access Nano Express

Effects of substrate annealing on the gold-catalyzed growth of ZnO nanostructures

Christian C Weigand1, Daniel Skåre2, Cecile Ladam3, Jostein Grepstad1 and Helge Weman1*

Author Affiliations

1 Department of Electronics and Telecommunications, Norwegian University of Science and Technology, 7491 Trondheim, Norway

2 Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway

3 SINTEF Materials and Chemistry, 7465 Trondheim, Norway

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Nanoscale Research Letters 2011, 6:566  doi:10.1186/1556-276X-6-566

Published: 26 October 2011

Abstract

The effects of thermal substrate pretreatment on the growth of Au-catalyzed ZnO nanostructures by pulsed laser deposition are investigated. C-plane sapphire substrates are annealed prior to deposition of a thin Au layer. Subsequent ZnO growths on substrates annealed above 1,200°C resulted in a high density of nanosheets and nanowires, whereas lower temperatures led to low nanostructure densities. Separate Au film annealing experiments at 700°C showed little variation in the size and density of the Au catalyst droplets with substrate annealing temperature. The observed variation in the density of nanostructures is attributed to the number of surface nucleation sites on the substrate, leading to a competition between nucleation promoted by the Au catalyst and surface nucleation sites on the rougher surfaces annealed below 1,200°C.

Keywords:
zinc oxide; laser ablation; atomic force microscopy; thermal annealing; vapourliquid-solid growth; nanostructures; surface roughness; surface defects