The experimental and theoretical studies of the local atomic order and chemical binding in tantalum oxide amorphous films are presented. The experimental studies were performed on thin films deposited at the temperature of 100 °C by atomic layer deposition on silicon (100) and glass substrates. Thin films of amorphous tantalum oxide are known to exhibit an extremely large extent of oxygen nonstoichiometry. Performed X-ray absorption and photoelectron studies indicated the oxygen over-stoichiometric composition in the considered films. Surplus oxygen atoms have 1s electron level with binding energy about 1 eV higher than these in reference Ta₂O₅ oxide. The density functional theory was applied to find the possible location of additional oxygen atoms. Performed calculation indicated that additional atoms may form the dumbbell defects, which accumulate the dangling oxygen bonds in orthorhombic structure and lead to increase of oxygen 1s level binding energy. The presence of this kind of oxygen–oxygen bonding may be responsible for increase of amorphous film chemical resistivity which is very important in many applications.

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO₂) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface.

This paper presents an investigation of properties of selected metallic oxides deposited at a low temperature (100 °C) by atomic layer deposition (ALD) technique, relating to their applicability as thin overlays for optical fiber sensors resistant in alkaline environments. Hafnium oxide (Hf _x O _y with y / x approx. 2.70), tantalum oxide (Ta _x O _y with y / x approx. 2.75) and zirconium oxide (Zr _x O _y with y / x approx. 2.07), which deposition was based, respectively, on tetrakis(ethylmethyl)hafnium, tantalum pentachloride and tetrakis(ethylmethyl)zirconium with deionized water, were tested as thin layers on planar Si (100) and glass substrates. Growth per cycle (GPC) in the ALD processes was 0.133–0.150 nm/cycle. Run-to-run GPC reproducibility of the ALD processes was best for Hf _x O _y (0.145 ± 0.001 nm/cycle) and the poorest for Ta _x O _y (0.133 ± 0.003 nm/cycle). Refractive indices n of the layers were 2.00–2.10 (at the wavelength λ = 632 nm), with negligible k value (at λ for 240–930 nm). The oxides examined by x-ray diffractometry proved to be amorphous, with only small addition of crystalline phases for the Zr _x O _y . The surfaces of the oxides had grainy but smooth topographies with root-mean square roughness ∼0.5 nm (at 10 × 10 μ m ² area) according to atomic force microscopy. Ellipsometric measurements, by contrast, suggest rougher surfaces for the Zr _x O _y layers. The surfaces were also slightly rougher on the glass-based samples than on the Si-based ones. Nanohardness and Young modules were 4.90–8.64 GPa and 83.7–104.4 GPa, respectively. The tests of scratch resistance revealed better tribological properties for the Hf _x O _y and the Ta _x O _y than for the Zr _x O _y . The surfaces were hydrophilic, with wetting angles of 52.5°–62.9°. The planar oxides on Si, being resistive even to concentrated alkali (pH 14), proved to be significantly more alkali-resistive than Al ₂ O ₃ . The Ta _x O _y overlay was deposited on long-period grating sensor induced in optical fiber. Thanks to such an overlay the sensor proved to be long-lasting resistant when exposed to alkaline environment with a pH 9. Thereby, it also proved that it has a potential to be repeatedly reused as a regenerable optical fiber biosensor.

Although Ta2O5 is thermodynamically the most stable form of TaxOy, the chemical composition/stoichiometry of TaxOy films may generally be complex. On the other hand, to be robust in harsh chemical environments, the film material is required to be amorphous rather than crystalline. The amorphousness of atomic layer deposited (ALD) films is promoted by low process temperature generally. This paper presents the study on TaxOy films deposited by ALD at low temperature (100 °C) using TaCl5 and H2O as chemical precursors, bringing the compositional, structural, and optical properties of the films together. The films with the thickness in the range of 32–202.5 nm were deposited mostly on Si (100) wafers. For their characterization, secondary ion mass spectroscopy, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, x-ray diffractometry, and spectroscopic ellipsometry were performed. The films were overstoichiometric in relation to Ta2O5, with the O/Ta ratio in the range of 2.7–2.8. Additionally, some amount of surface O was bound within adsorbed -OH and -CO groups. The main contaminant of the films was Cl (5–5.5 at. %). The main contaminant of their surfaces and at the film/substrate interfaces was carbon (>50 at. %). All the films proved to be fully amorphous. Their real part of refractive index was very similar (n approximately 2) in the whole range of thicknesses, with differences of a few percent only. Optical attenuation was negligibly low.