[en] Zirconium doped indium oxide thin films were deposited by the atomic layer deposition technique at 500 deg. C using InCl₃, ZrCl₄ and water as precursors. The films were characterised by X-ray diffraction, energy dispersive X-ray analysis and by optical and electrical measurements. The films had polycrystalline In₂O₃ structure. High transparency and resistivity of 3.7x10^-4 Ω cm were obtained

[en] In this paper, the possibilities of rare-earth oxides as gate dielectrics are discussed. The thin films have mostly been fabricated by physical vapor deposition methods. The rare earths most often studied are yttrium, lanthanum and gadolinium. The deposition of the gate oxide should be carried out under mild conditions, and therefore chemical deposition techniques are preferred. Atomic layer deposition of rare-earth oxides is introduced and special attention is given to the volatile precursors and deposition processes. The electrical properties of rare-earth oxide gate oxides will be highlighted. The results obtained are encouraging and the use of rare-earth oxides in gate stacks is possible. Especially, they may be important in connection to III-V compounds

[en] Stoichiometric HfO₂ films were atomic layer deposited from HfI₄ and HfCl₄ at 300 deg. C on p-Si(1 0 0) substrates. Water was in both cases used as an oxygen precursor. The films consisted dominantly of monoclinic HfO₂ phase. Additional tetragonal HfO₂ could be detected only in the films grown from HfCl₄. Effective permittivities were frequency-independent and varied in the range of 12-14, without clear dependence on the precursor used. Oxide rechargeable trap densities were relatively high for the films grown from HfCl₄. The films grown from HfI₄ were more resistant against breakdown. The films grown from either precursor contained 0.4 at.% of halide residues and 1.0-1.5 at.% hydrogen. Annealing in forming gas at 400 deg. C did not affect the film composition. The growth rate was somewhat more stable in the HfI₄ based process

[en] Calcium carbonate (CaCO_3) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO_3)_2·4H_2O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO_3 fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO_3 layer by spin or dip coating Ca(NO_3)_2/PVP precursor solution on the CaCO_3 fibers followed by annealing of the gel formed inside the fiber layer. The CaCO_3 fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings. - Highlights: • Calcium carbonate fibers were prepared by electrospinning. • The electrospun fibers crystallized to calcite upon calcination at 500 °C. • Spin and dip coating methods were used to improve the adhesion of the CaCO_3 fibers. • The CaCO_3 fibers were converted to hydroxyapatite by treatment in phosphate solution. • The hydroxyapatite fibers consisted of plate-like nanocrystals

[en] Hf-Si-O mixture films were fabricated by atomic layer deposition at 400 deg. C on Si(1 0 0) substrates. The deposition sequence for one hafnium silicon oxide submonolayer comprises surface reactions between Si(OC₂H₅)₄ and HfCl₄, followed by the hydrolysis step in order to effectively remove the residual ligands. The effective permittivity, leakage current, and capacitance-voltage behavior depended on the hafnium/silicon ratio and on the oxide/silicon interface quality. The dielectric quality can be modulated for various configurations of stacked layers with different hafnium to silicon ratios

[en] Quartz crystal microbalance (QCM) is a very powerful method for in situ monitoring of thin film growth processes. However, especially at high temperatures, QCM is very sensitive to already minor temperature changes during the measurement. Here, a method for compensating the temperature effects on the QCM is introduced. In this method, the baseline drift during the growth is calculated using a function obtained by fitting the signal measured before and after the growth. The present method is compared with the earlier published reference crystal method where two closely spaced quartz crystals are used, one being protected against film growth and thus serving as a reference crystal for compensating the temperature effects on the measurement crystal. Both methods were tested with TiO₂ and Al₂O₃ atomic layer deposition processes and the temperature effect was successfully compensated. The differences between these methods are discussed

[en] Potassium cobalt hexacyanoferrate(II) [K${}_2$CoFe(CN)${}_6$] is an extremely selective ion exchanger for cesium ions. To examine the atomic level background for the selectivity a computational structural study using DFT modelling was carried out for K${}_2$CoFe(CN)${}_6$ and for products where Cs has replaced K in the elemental cube cages closest to the surface. In the K-form compound the potassium ions are not in the center of the Co-Fe-CN elementary cube cages closest to the surface but locate about 140 pm from the cube center towards the surface. When cesium ions are exchanged to these potassium ions they locate much deeper from the surface, being only about 70 pm upwards from the cube center. This apparently leads to much stronger bonding of cesium compared to potassium. Once taken up into the outermost cube cages on the surface of the crystallites cesium ions are not able to penetrate further since they are much larger than the electron window between the cubes. Furthermore, they are not able to return to the solution phase either leading to a practically irreversible sorption.

[en] Nanotubular Ta₂O₅- and TiO₂-based structures were prepared by atomic layer deposition of Ta₂O₅ and TiO₂ thin films, conformally on pore walls of porous alumina membranes. Both self-supporting alumina membranes and Si-supported thin-film membranes were studied as templates. Long Ta₂O₅ and TiO₂ nanotubes were prepared successfully with the self-supporting membranes. The TiO₂ nanotubes showed photocatalytic activity in methylene blue degradation under UV illumination. The Ta₂O₅ and TiO₂ nanotubes were further modified by depositing Pt nanoparticles inside them. The Si-supported thin-film membranes were used as templates for the preparation of robust Ta₂O₅-coated Ni nanorod arrays on a Si substrate using electrodeposition, chemical etching and atomic layer deposition. In addition to photocatalysis, the nanostructures prepared in this work may find applications as other catalysts and as solid-state or electrochemical capacitors.

[en] 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. (paper)

[en] A versatile synthesis procedure for composite nanofibers, combining electrospinning and atomic layer deposition (ALD), is presented. Both solid core/sheath nanofibers and nanoparticle loaded nanotubes can be made, depending on the order of calcination of the electrospun fiber and the ALD process. Magnetic and photocatalytic nanofibers prepared this way can be recycled readily by collecting with a magnet.