Highly-ordered growth of solution-processable ZnO for thin film transistors

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Date
2017-05
Authors
Buckley, Darragh
McNulty, David
Zubialevich, Vitaly Z.
Parbrook, Peter J.
O'Dwyer, Colm
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Electrochemical Society
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Abstract
We demonstrate that crystalline, epitaxial-like and highly ordered ZnO thin films and quasi-superlattice structures can be achieved from a precursor liquid at relatively low temperature via spin-coating. The synthesised films are smooth, stoichiometric ZnO with controllable thickness. An iterative layer-by-layer coating schematic is employed to demonstrate the effects of film thickness on structure, morphology as well as the surface and internal defects. Characterisation of the crystallinity, morphology, O-vacancy formation, stoichiometry, surface roughness and thickness variation was determined through X-ray diffraction, scanning and transmission electron and atomic force microscopy, X-ray photoelectron and photoluminescence spectroscopy. We demonstrate that iterative spin-coating of deposited ZnO films results in a transition in crystal texture with increasing thickness (number of layers) from the [ ] m-plane to the [ ] c-plane. The films attain a c-axis preferential orientation, with no other crystalline peaks present. Results show that the film’s surface morphology was very smooth, with average rms roughness <0.15 nm. Examination of these films also shows the consistency of the surface composition and defect level while highlighting the effect of temperature and cumulative annealing condition on the internal defect concentration.
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Thin films , Annealing condition , Effect of temperature , Preferential orientation , Solution processable , Super-lattice structures , Thickness variation , Transmission electron , X-ray photoelectrons , Atomic force microscopy , Coatings , Crystalline materials , Film growth , Metallic films , Morphology , Photoluminescence spectroscopy , Surface defects , Surface roughness , Temperature , Thin film circuits , X ray diffraction , Zinc oxide
Citation
Buckley, D., McNulty, D., Zubialevich, V. Z., Parbrook, P. J. and O'Dwyer, C. (2017) 'Highly-Ordered Growth of Solution-Processable ZnO for Thin Film Transistors', ECS Transactions, 77(4), pp. 99-107. doi: 10.1149/07704.0099ecs
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© 2017 ECS - The Electrochemical Society