Solution Epitaxy of TiO[sub 2] Thin Films

Abstract

Epitaxial anatase TiO2 thin films were grown on (001)-oriented single-crystal SrTiO3 substrates by liquid-phase deposition at 150°C . The out-of-plane alignment of the film was found to be at least 1 order of magnitude better than many other anatase films grown at much higher temperatures. The films were very smooth and made of nanosized crystallites, formed by a repeated nucleation mechanism rather than the oriented-attachment mechanism. The films also exhibited very large dielectric dispersions, which were largely attributed to dipolar and interfacial polarizations of hydroxyl groups and water molecules.

Growth of Epitaxial Anatase Nano Islands on SrTiO3(001) by Dip Coating

“…Thus, anatase films could be grown on SrTiO 3 (001) or LaAlO 3 (001) by electron beam evaporation for substrate temperatures between 500 and 1000 °C, although growth on SrTiO 3 (001) at 1100 °C led to a mixture of anatase and rutile phases. 29 Epitaxial films have also been grown on these substrates by low temperature solution based deposition techniques 30,31 or by hydrothermal dissolution of SrO out of SrTiO 3 . 32 In the present communication, a very simple and inexpensive wet chemical procedure is used to prepare the TiO 2 films, which crystallize into small islands of the anatase phase upon thermal annealing at 1000 °C.…”

Hydrothermal epitaxy of ferromagnetic cobalt doped titanium dioxide films at 120 °C

“…It shows that the film is composed of nanosized islands and suggests that the film is polycrystalline and not epitaxial. But as demonstrated previously by Chan and Goh 11 for solution grown undoped TiO 2 films at 150 C, epitaxial TiO 2 films with such morphology can be grown by a repeated nucleation mechanism. The epitaxial nature of the film is also verified in the present work as confirmed in the following paragraph on X-ray diffraction studies.…”

“…The fluoride ligand allows a gradual and more controllable hydrolysis as boric acid acts as F-scavengers. 10 This technique does not require the use of vacuum systems or post-deposition calcination to obtain crystalline films and has previously been used to deposit epitaxial TiO 2 , ZnO and perovksite films at <200 C. [11][12][13] More importantly, this report shows that the growth solution provides an oxidizing environment that excludes the possibility of metallic cluster formation in the film.…”

Toward Dynamic Control over TiO2 Nanocrystal Monolayer-by-Monolayer Film Formation by Electrophoretic Deposition in Nonpolar Solvents

“…Nanocrystals (NCs) of anatase titanium dioxide (TiO 2 ) have increasingly been employed in thin films due to their attractive size-dependent optical properties in dye-sensitized solar cells, photocatalysis, photochromic and electochromic devices, batteries, and other applications. − Precise control of the morphology and the size of these nanoscale materials is central to the fine-tuning of their physical properties, such as electrical conductivity, magnetic coercivity, optical absorbance, and mechanical strength. TiO 2 thin films, both nanostructured and single crystalline, have been prepared using a variety of process including plasma enhanced chemical vapor deposition, sputtering, , metal organic chemical vapor deposition, spray pyrolysis, chemical bath deposition, electrochemical deposition, , electrophoretic deposition (EPD), − sol–gel, and photodeposition . Of the aforementioned techniques, EPD is one of the more promising for the assembly of nanocrystals.…”