TEM of atomic layer deposition TiO2
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Date
2002-02-04
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Australian Society for Electron Microscopy
Abstract
Since the development of the atomic layer deposition (ALD) technique in the 1970s it has been widely used for the deposition of a range of binary, ternary and quaternary thin film systems (Niinisto 1996). The distinguishing feature of ALD is that the surface reactions are self limiting. Precursors saturate the adsorption sites, excess precursor is purged, followed by a pulse of reactant to form the film in-situ. Repetition of this deposition cycle permits films to be deposited to the desired thickness. Since the process is driven by adsorption, it produces films with outstanding conformality with the substrate (Ritala and Leskela, 1999), albeit at the expense of very slow deposition rates ( 50nm/hour). Following the recent commissioning of an ALD deposition system, we have been developing our expertise in the deposition and characterisation of TiO2 films in the first instance. These have potential uses in applications such as optical coatings, photovoltaics, sensors and catalysts. The focus of this paper is to report our plan view and cross-sectional transmission electron microscopy (TEM) studies on these films. Despite the power of the TEM technique, it has enjoyed very limited application to the study of any ALD films to date. Our results describe a detailed picture of the evolution of the film morphology under the influence of deposition temperature and surface chemistry of the substrate. These factors influence the nucleation of crystallisation within the films. Plasmon imaging, energy filtered imaging and electron energy loss spectroscopy enable the films to be characterised at the nanometer scale. ©2002 Australian Society for Electron Microscopy Inc
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Keywords
Crystallization, Energy-loss spectroscopy, Nucleation, Structural chemical analysis, Surface coating, Temperature dependence, Thin Films, Titanium oxides, Transmission electron microscopy
Citation
Mitchell, D. R. G., Attard, D. J., & Triani, G. (2002). TEM of atomic layer deposition TiO2. Presentation to the ACEM17: 17th Australian Conference on Electron Microscopy, Adelaide, South Australia, Monday 4th - Friday 8th February 2002. In J. Terlet & M. Dayman, (Eds), ACEM17: 17th Australian Conference on Electron Microscopy, Monday 4th - Friday 8th February 2002, Adelaide Convention Centre, Adelaide, South Australia : program and abstract book , (p. 86). Adelaide: Australian Society for Electron Microscopy .