title: Atomic Layer Deposition for Coating of High Aspect Ratio TiO2Nanotube Layers.
abstract: We present an optimized approach for the deposition of Al2O3(as a model secondary material) coating into high aspect ratio (≈180) anodic TiO2nanotube layers using the atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al2O3precursors on the resulting coating thickness, ALD processes with different exposure times (i.e., 0.5, 2, 5, and 10 s) of the trimethylaluminum (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 s), as verified by detailed scanning electron microscopy analysis. Quartz crystal microbalance measurements were used to monitor the deposition process and its particular features due to the tube diameter gradient. Finally, theoretical calculations were performed to calculate the minimum precursor exposure time to attain uniform coating. Theoretical values on the diffusion regime matched with the experimental results and helped to obtain valuable information for further optimization of ALD coating processes. The presented approach provides a straightforward solution toward the development of many novel devices, based on a high surface area interface between TiO2nanotubes and a secondary material (such as Al2O3).
authors.affiliation: Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice , Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.
authors.forename: Raul
authors.initials: R
authors.lastname: Zazpe
authors.affiliation: Institute of Semiconductors and Microsystems and Center for Advancing Electronics Dresden (cfaed), Noethnitzer Str. 64, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Knaut
authors.affiliation: Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice , Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.
authors.forename: Hanna
authors.initials: H
authors.lastname: Sopha
authors.affiliation: Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice , Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.
authors.forename: Ludek
authors.initials: L
authors.lastname: Hromadko
authors.affiliation: Institute of Semiconductors and Microsystems and Center for Advancing Electronics Dresden (cfaed), Noethnitzer Str. 64, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Albert
authors.affiliation: Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice , Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Prikryl
authors.affiliation: Laboratory of Nanostructures and Nanomaterials, Institute of Physics of the CAS , v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic.
authors.forename: V
authors.initials: V
authors.lastname: Gärtnerová
authors.affiliation: Institute of Semiconductors and Microsystems and Center for Advancing Electronics Dresden (cfaed), Noethnitzer Str. 64, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Johann W
authors.initials: JW
authors.lastname: Bartha
authors.affiliation: Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice , Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Macak