Two kinds of TiO2 nanostructures, i.e., TiO2-coated alumina membranes and TiO2-coated Ni nanowires, were prepared by combining different kinds of porous alumina, template-directed electrodeposition and atomic layer deposition. The photocatalytic activities of the nanostructures were tested with methylene blue degradation under UV illumination. All structures showed photocatalytic activity, and the efficiency of the photocatalytic performance was found to be a strong function of the dimensions of the nanostructure.

Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films.

Tin oxide thin films were grown by atomic layer deposition (ALD) from bis[bis(trimethylsilyl) amino]tin(II) with ozone and water. The ALD growth rate of tin oxide films was examined with respect to substrate temperature, precursor doses, and number of ALD cycles. With ozone two ALD windows were observed, between 80 and 100 C and between 125 and 200 C. The films grown on soda lime glass and silicon substrates were uniform across the substrates. With the water process the growth rate at 100-250 C was 0.05-0.18 Å /cycle, and with the ozone process, the growth rate at 80-200 C was 0.05-0.11 Å /cycle. The films were further studied for composition and morphology. The films deposited with water showed crystallinity with the tetragonal SnO phase, and annealing in air increased the conductivity of the films while the SnO 2 phase appeared. All the films deposited with ozone contained silicon as an impurity and were amorphous and nonconductive both as-deposited and after annealing. The films were further deposited in TiO 2 nanotubes aiming to create a pn-junction which was studied by I-V measurements. The TiO 2 nanostructure functioned also as a test structure for conformality of the processes. V

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Titanium dioxide nanotubes were grown from titanium foil by anodization in ethylene glycol solutions containing water, ammonium fluoride and ethylenediaminetetraacetic acid (EDTA). Different anodization voltages and times were used and the properties of the grown nanotubular films were compared with the films anodized without EDTA. It was shown that it is possible to affect the size and volume of the TiO 2 nanotubes in a straightforward manner by adding EDTA to the anodization solution. EDTA enhanced the surface area of the TiO 2 structure by accelerating the dissolution of TiO 2 by releasing fluoride ion from its titanium complexes.