Effect Of Oxygen Incorporation Research Articles

Evaluation of the effect of oxygen incorporation on the thermo–chemical–mechanical properties of the proton-conducting oxide BaZr0.8Yb0.2O3-δ

This study aims to evaluate the effects of multiple defect species produced by water and oxygen incorporation on the lattice parameters of BaZr0.8Yb0.2O3-δ (BZYb20) and model its chemical expansion considering these effects. In this study, the lattice constant of BZYb20 was investigated under oxygen partial pressure (pO2 = 1–10−3 bar), water vapor partial pressure (pH2O = 0.0023 bar and dry) and over a wide range of temperatures (473–1173 K) using two approaches: model calculations and high-temperature X-ray diffraction (HT-XRD). HT-XRD measurements revealed that the lattice expansion of BZYb20 changed within 700–900 K in a humidified atmosphere. In a nonhumidified atmosphere, this temperature range shifts lower. High-temperature gravimetric measurements of oxygen incorporation showed that the change in oxygen vacancy concentration was sufficiently small, and the effect of oxygen incorporation on the lattice constant was negligible. High-temperature gravimetric measurements of water incorporation yielded thermodynamic parameters for the hydration reaction. Based on these results, the HT-XRD results were reproduced by fitting a lattice constant model that neglects the effects of oxygen. Therefore, the effect of oxygen incorporation on chemical expansion can be ignored, and the chemical expansion can be estimated using the model developed in this study.

Effect of oxygen on the crystallinity and defect state of AlxGa1−xN epilayers

The effect of oxygen incorporation on the crystal quality and defect states in AlxGa1−xN epilayers (x = 0.4, 0.6, 0.8) grown by hydride vapor phase epitaxy with and without oxygen gas flow were studied. On the basis of the full width at half-maximum value of the (102) X-ray diffraction rocking curve, the crystal quality of AlxGa1−xN with oxygen was better than that of AlxGa1−xN without oxygen as the Al/Ga ratio increased. In Al0.6Ga0.4N epilayers with and without oxygen, two deep traps of H1ʹ and H2ʹ were measured by deep level transient spectroscopy. All traps were hole-like traps with activation energies of 1.28 eV (H1ʹ) and 0.61 eV (H2ʹ), which are the same as traps H1 and H2 measured in Al0.4Ga0.6N. Al0.8Ga0.2N with oxygen had only the D1 trap, as observed by thermally stimulated current, while the sample without oxygen has two traps of D1 (0.80 eV) and D2 (0.64 eV). The trap densities in AlxGa1−xN epilayers decreased with oxygen as the Al mole fraction increased in AlxGa1−xN. Therefore, the oxygen atoms can improve the crystal quality and suppress the defect states in AlxGa1−xN epilayers.

Effect of oxygen incorporation on dynamic magnetic properties in Ta-O/Co-Fe-B bilayer films under out-of-plane and in-plane magnetic fields

Dynamic magnetic properties of Ta-O/Co20Fe60B20 bilayer films are strongly influenced by the oxidation condition of the Ta-O layer. The oxidation of the Ta-O layer by a slight amount of oxygen with a pressure (POxygen) of 0.03 Pa decreases in-plane damping constant (αIP), and increases the effective magnetization (4πMs,eff). Then, both αIP and 4πMs,eff maintain their values by increasing POxygen up to 0.3 Pa. The out-of-plane damping constant (αOP) showed a similar tendency to that of αIP against POxygen, although αOP is much smaller than αIP in every POxygen. αOP reaches to 0.0033 for sample oxidized at 0.03 Pa. It was suggested that αIP consists of both the intrinsic damping and the extrinsic damping, while αOP is closer to the intrinsic damping. The control of αOP and αIP by the oxidation would be beneficial in designing the high frequency spintronic devices.

Oxygen-incorporated molybdenum disulfide nanosheets as electrode for enhanced capacitive deionization

Molybdenum disulfide (MoS2) has emerged as a promising electrode for capacitive deionization (CDI) process. Increasing intrinsic conductivity of MoS2 is critical for further improvement of CDI performance. In this work, the effects of oxygen incorporation in MoS2 nanosheets on CDI performance were investigated. High-electronegative oxygen heteroatom incorporation into MoS2 nanosheets was realized via a facile hydrothermal method. The oxygen-incorporated MoS2 generated a dramatically improved CDI performance compared to pristine MoS2 nanosheets. The optimized MoS2 electrode with moderate degree of oxygen incorporation (2.91 at.%) exhibited the highest desalination capacity of 28.85 mg/g in 500 mg/L NaCl solution. The enhancement was found that oxygen incorporation could effectively improve the intrinsic conductivity and expose more active sites, leading to a higher specific capacitance and lower inner resistance. Besides, the oxygen-incorporated MoS2 with achieved balance between structure and active sites could reach the highest desalination capacity. This finding indicated that heteroatom incorporation into MoS2 could be a new way to enhance CDI performance.

Effects of oxygen incorporation in low expansion Ni+CrAlYN nanocomposite coatings on the oxidation behavior

Low-expansion Ni + CrAlYN and Ni + CrAlYNO nanocomposite coatings were prepared by reactive vacuum arc evaporation using a NiCrAlY target in N2 and mixture of N2 + O2, respectively. After 500 h oxidation tests, the Ni + CrAlYN coating degraded to almost a metallic one and segregation of substrate elements, e.g. Co, Ti and Mo, in the alumina scale was observed. By contrast, the outer parts of the Ni + CrAlYNO coatings still contained lots of nano-sized AlN particles, and few impurities were detected in TGO. Thus, oxygen incorporation in the nanocomposite coatings improved the oxidation resistance by slowing down the coating degradation.

Influence of growth conditions and film thickness on the anodization behavior of sputtered aluminum films and the fabrication of nanorod arrays

This paper reports on how both the growth conditions and thickness of aluminum thin films impact the surface morphology and subsequent anodization behavior when sputtered onto Si and glass substrates up to a 1-μm thickness, respectively. Specifically, the effects of oxygen incorporation during sputtering and variations between continuous vs. stepwise deposition are thoroughly investigated here. Previous studies demonstrated the tremendous impact of oxygen concentration while sputtering, which, in turn, allows minimizing the grain sizes for 200-nm-thick sputtered AlOX-films. The then anodized aluminum oxide (AAO) thin films can then be used, for instance to grow quasi defect-free, large-area gold nanorod arrays for plasmonic applications. The challenge when preparing thicker films as emphasized here, is to avoid gradients of oxygen concentration and grain size for any film thickness. We have developed reproducible protocols how to minimize such gradients: the deposition process is purposely interrupted after every 100/200/300-nm AlOX deposition step for approximately 5 min. to allow thermal relaxation under pure nitrogen atmosphere. The subsequent anodization and pore filling with gold then revealed highly improved properties for AAO-films up to the 1-μm thickness, exhibiting a homogenous nanorod distribution with a very low number of defects.

P-type conduction in two-dimensional MoS2 via oxygen incorporation

The effects of oxygen incorporation on the electronic transport properties of two-dimensional (2D) MoS2 have been studied via temperature dependent and gate voltage dependent transport measurements of physical vapor deposited 2D MoS2. Gated micro-van der Pauw cross devices were fabricated from the MoS2 film for transport measurements. Field-effect measurements indicate that incorporated oxygen acts as a p-type dopant for MoS2. The combination of X-ray photoemission spectroscopy surface analysis and Raman measurements of the film indicates that acceptor states resulting from MoSxO3-x inclusions in the MoS2 film are the origin of the p-type doping. Temperature dependent van der Pauw conductivity measurements indicate an acceptor energy of 214 meV above the valence band edge for the acceptor state.

Investigation on the crystallization properties and structure of oxygen-doped Ge8Sb92 phase change thin films

Effects of oxygen incorporation on the crystallization characteristics and crystal structure of Ge8Sb92 films were systematically investigated. The amorphous-to-crystalline transition was studied by in situ resistance measurement. The thermal stability, electrical resistance and band gap of Ge8Sb92 material increase significantly by the addition of oxygen. X-ray diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy illustrate that a small amount of oxygen dopant can inhibit the grain growth and limit the grain size because of the formation of Ge and Sb oxide. Atomic force microscopy and x-ray reflectivity results indicate that the film surface becomes smoother and the film thickness change becomes smaller after oxygen doping. Phase change memory cells based on oxygen-doped Ge8Sb92 film were fabricated to evaluate the electrical properties as well. All the results demonstrate that suitable incorporation of oxygen is an effective way to enhance the comprehensive performance of Ge8Sb92 thin films for phase change memory application.

Effect of oxygen incorporation in the Mg2Si lattice on its conductivity type – A possible reason of the p-type conductivity of postannealed Mg2Si thin film

We examined the possible reasons for the p-type conductivity of undoped, post-annealed Mg2Si thin film prepared by sputtering deposition process. Since it would not be able to explain the results by taking only recovery of the lattice defects into consideration, we paid attention to the possible oxygen(O)-incorporation through substitutional reaction of Mg and Si by O and O-intercalation into the 4b site of Mg2Si lattice. Energetic evaluations by using 1st principle calculations showed that O- intercalation is the most probable reaction and this would cause p-type conductivity because oxygen in Mg2Si will work as a recipient of electrons.

Structural and optoelectronic characteristics of nanocrystalline silicon oxide film as absorber layer for thin film solar cells

The mixed phase nanocrystalline silicon oxide (nc-SiOx:H) thin films have been prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) system from SiH4, H2 and CO2 mixture. The effect of oxygen incorporation on the structural and opto-electrical properties of nc-Si:H films was investigated. As the CO2 flow rate increased, the crystalline volume fraction in the films decreased, while the optical band gap increased slowly. During the phase transition, both oxygen and hydrogen content increased drastically with the increasing CO2 flow rate, while the Urbatch energy and microstructure factor showed obvious reduction, which indicated an enhancement of the medium range order of the films and good passivation of the inner voids. Device quality nc-SiOx:H film was fabricated with low microstructure factor of 0.32 and high crystalline volume fraction around 50%, along with wide optical band gap of ∼1.75 eV, low dark-conductivity σd ∼7.6 × 10−6 S/cm and high photosensitivity of about 2 × 102. On flat substrate a solar cell was prepared with high Voc of 0.62 V and Jsc of 14.57 mA/cm2. These results revealed the potential of nc-SiOx:H film as an absorber layer for thin film solar cells.

Effects of oxygen incorporation in solar cells with a-SiOx:H absorber layer

The effects of oxygen incorporation on layer properties and cell performance were investigated in thin film solar cells with a-SiOx:H absorber layers. Besides the widened optical band gap and increased defect densities, a doping effect is observed upon oxygen incorporation even for the layers with wide band gap. From comparison of solar cells illuminated from either p- or n-side, we conclude that overall hole carrier collection is strongly deteriorated by increasing the oxygen concentration. The donor-like states induced by oxygen reform the electric field in the absorber. The intensified electric field near the p/i interface improves the quantum efficiency (QE) around 400 nm, which is attributed to the better carrier collection in the p-layer. The maximum of QE shows a blue shift with both p- and n-side illumination. It is consistent with the enhanced optical band gap of the absorber layer and shows the potential of usage in multi-junction solar cells.

Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

Effect of oxygen incorporation in a-plane GaN on p-type ohmic contact property

We report on the origin of the non-ohmic behavior of Ni/Au-based p-type contacts on a nonpolar a-plane GaN layer. The contact properties of Ga-polar c-plane GaN and nonpolar a-plane GaN are compared. While the Ga-polar c-plane shows ohmic-contact properties in the Ni/Au contact after heat treatment, the nonpolar a-plane shows rectifying characteristics both before and after heat treatment. We determined the reasons why the two planes show substantial differences in contact properties using various tools. We conclude that the differences originated from the oxygen incorporation preference resulting in gallium oxide formation at the interface of nonpolar a-plane GaN.

Effects of Oxygen Incorporation on the Physical Properties of Amorphous Metal Thin Films

Incorporated oxygen is known to affect amorphous metal thin film (AMTF) mechanical properties, but comparatively little is known about how it affects their structural characteristics and electrical transport properties. In this study, AMTFs are produced by using sputter deposition. Chemical composition, average interatomic spacing, surface roughness, and electrical transport properties are examined using electron probe microanalysis (EPMA), X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and variable-temperature resistivity. ZrCuAlNi amorphous metal thin films exhibit a temperature dependence that is characteristic of d-electron conduction and electrical resistivity that increases substantially with increasing oxygen content. TiAl and ZrCuB are found to be sp-electron conductors with electrical resistivity that decreases with increasing oxygen content. The surface roughness of all films increases with oxygen content, whereas interatomic spacing is relatively insensitive to incorporated oxygen content. The relationships among amorphous metal composition, structural characteristics, and electrical transport properties are discussed.

Effect of oxide shells on the magnetic and magnetotransport characteristics of oxidized FeCoZr nanogranules in Al 2O 3

The paper reports on the results of a comparative study of magnetic and magnetotransport properties of granular nanocomposite films FeCoZr–Al 2O 3 synthesized in pure Ar and Ar + O sputtering atmosphere. Effects of oxygen incorporation on the temperature and magnetic field dependencies of magnetization and electrical resistance of the films are discussed with respect to the “core–shell” structure formation. Peculiarities of coercive force variation with temperature are analyzed and discussed.

Effect of Oxygen Incorporation into Cyclohexanone Ring on Antifeedant Activity

Effect of Oxygen Incorporation into Cyclohexanone Ring on Antifeedant ActivityThe behaviour of the peach potato aphidMyzus persicae(Sulz.) was studied during settling on plants. The experiment involved observing peach potato aphid activity after the application of some natural and synthetic cyclohexanones and the, respective ε-lactones and epoxy-ε-lactones which were obtained from the cyclohexanones. Stereochemistry, and the number and position of methyl substituents were important for the biological activity of the starting compounds: only trimethyl-substituted cyclohexanones were active,i.e.3.3.5-trimethylcyclohexanone (deterrent) and 2.2.6-trimethylcyclohexanone (attractant). The effect of oxygen incorporation into the cyclohexanone ring on deterrent activity varied depending on the starting compound. The ε-lactones that derived from saturated cyclohexanones were either weak attractants or were inactive, except the deterrent ε-lactone with three methyl groups at positions 3.7.7. None of the products of unsaturated ketone isophorone (weak deterrent) oxidation,i.e.epoxy isophorone, epoxy lactone, or unsaturated lactone, affected aphid settling. Of the two epoxy ketones obtained from (+)-dihydrocarvone that was inactive, only (2S, 5S)-2-methyl-5-((S)-1-methyloxiranyl)-cyclohexanone was a strong deterrent. Both epoxy-ε-lactones that derived from (+)-dihydrocarvone were strong deterrents.

Effects of oxygen incorporation in GeSbTe films on electrical properties and thermal stability

Oxygen incorporated Ge2Sb2Te5 (GST) films were prepared by an ion beam sputtering deposition method. I-V curves of the oxygen incorporated GST active layer showed that the threshold voltage (Vth) varied, depending on the level of incorporated oxygen. In the case of a GST film with an elevated oxygen content of 30.8%, the GST layer melted at 9.02 V due to the instability conferred by the high oxygen content. The formation of Ge-deficient hexagonal phases such as GeSb2Te4 and Sb2Te3 appear to be responsible for the Vth variation. Impedance analyses indicated that the resistance in GST films with oxygen contents of 16.7% and 21.7% had different origins. Thermal desorption spectroscopy data indicate that moisture and hydrocarbons were more readily desorbed at higher oxygen content because the oxygen incorporated GST films are more hydrophilic than undoped GST films.

Effect of oxygen incorporation on normal and superconducting properties of MgB2 films

Oxygen was systematically incorporated in MgB2 films using in situ postgrowth anneals in an oxygen environment. Connectivity analysis in combination with measurements of the critical temperature (Tc) and resistivity (ρ) indicate that oxygen is distributed both within and between the grains. High values of critical current densities (Jc) in field (∼4×105A∕cm2 at 8T and 4.2K), extrapolated critical fields [Hc2(0)] (>45T), and slopes of critical field versus temperature (1.4T∕K) are observed. Our results suggest that low growth temperatures (300°C) and oxygen doping (⩾0.65%) can produce MgB2 with high Jc values in field and Hc2 for high-field magnet applications.

The effect of oxygen incorporation in sputtered scandium nitride films

Thin films of the semiconductor scandium nitride were deposited onto sapphire substrates using reactive magnetron sputtering. Increasing concentrations of oxygen were introduced into the ScN films via increasing the residual base pressure in the deposition chamber prior to introduction of the reactive Ar/N 2 sputtering gas mixture. Films showed significant oxygen contamination even when deposited using base pressures of 10 − 6 Pa. Increasing levels of contamination degrade the crystalline quality of the films. Oxygen contamination also contributes to the non-Arrhenius behaviour of film resistivity versus temperature and ultimately results in degenerate n-type conductivity in the ScN films. Oxygen incorporation in ScN increases the direct band gaps from 2.2 eV to 3.1 eV and may therefore be a contributing reason for the wide range of direct band gaps experimentally determined for this material. Comparison with TiN and ZrN films deposited under similar conditions shows that ScN displays a comparatively high oxygen affinity. The results imply that the production of ScN films possessing high crystalline quality and non-degenerate electrical properties requires the use of deposition techniques involving ultra-high vacuum conditions or other low-oxygen environments.

Tuning of magnetic properties and structure of granular FeCoZr–Al2O3 nanocomposites by oxygen incorporation

Abstract Effect of oxygen incorporation on the magnetic properties and structure of (FeCoZr) x (Al 2 O 3 ) 1− x (17% x