Heat treatment effects on the surface morphology and optical properties of ZnO nanostructures

Abstract

AbstractZinc oxide (ZnO) nanostructures have received broad attention due to its wide applications especially for thin‐film solar cells and transistors. In this paper, we report the effects of heat treatment on the structural and optical properties of ZnO nanostructures. Zinc oxide nanostructures were synthesized using thermal chemical vapour deposition (CVD) method on glass substrate. The surface morphologies which were observed by scanning electron microscope (SEM) show that ZnO nanostructures change its shape and size when the annealing temperature increases from 400 °C to 600 °C. Structural measurement using X‐ray diffraction (XRD) has shown that ZnO nanostructures have the highest crystallinity and smallest crystallite size (20 nm) when annealed at 550 °C. Furthermore, the samples were optically characterized using Photoluminescence (PL) spectrometer. The PL spectra indicate that ZnO nanostructures have the highest peak at UV wavelength when annealed at 550 °C. The mechanism of the PL properties of ZnO nanostructures is also discussed. We conclude that ZnO nanostructures deposited using thermal CVD have the optimum structural and PL properties when annealed at 550 °C. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)