Formation Of Oxynitride Research Articles

The effect of MEVVA ion implantation of Zr on the corrosion behaviour of PVD TiN coatings

The use of TiN coatings as corrosion barriers is limited by the presence of defects such as pin-holes. In this study Zr ions were implanted into PVD deposited TiN coatings at varying doses, to improve the corrosion resistance. The corrosion behaviour was assessed in saline environments using linear polarisation techniques and the corroded surface of the coatings characterised using XPS and SEM. Overall, ion implantation resulted in an increase in the coating’s corrosion resistance. Protection was attributed to closure of existing pin-holes and the formation of various nitrides, oxides and oxynitrides of Ti and Zr.

The interaction of uranium metal with nitrogen oxides: The formation of an oxynitride surface layer

The interaction of nitric oxide, nitrogen dioxide and nitrous oxide with a polycrystalline uranium surface has been investigated at 298 K. The surface composition and electronic structure of the developing oxide films were studied using X-ray and ultraviolet photoelectron spectroscopy. Nitrous oxide adsorbs dissociatively leaving only oxygen adsorbed on the uranium surface. Nitric oxide and nitrogen dioxide also adsorb dissociatively but in these cases both oxygen and nitrogen remain on the surface. We propose the formation of uranium oxynitride (UO x N y ). For exposures >350 L the rate of reaction of NO with the oxynitride surface decreases significantly. In contrast, NO 2 continues to react with the surface and a further increase in surface oxygen concentration is observed.

Hardness and tribology measurements on ZrN coatings deposited by reactive sputtering technique

ZrN coatings have been grown in an rf sputtering deposition chamber, using different ratios of Ar/N 2 (5/1, 5/5, 1/5) in the reactive gas flow. After deposition, the coatings were thermally treated in a 500 °C oxygen atmosphere, in order to test the thermal stability of the layers or the oxynitride formation. The chemical composition, surface roughness and structural, mechanical and tribological properties of the as-deposited and annealed samples have been measured by energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffractometry, nanoindentation and pin-on-disk techniques, respectively. Deposition parameters determine the growth rate, crystalline structure and surface roughness, which affect the mechanical and tribological behaviour of the samples. The best mechanical and tribological performance and highest growth rate was found for the sample grown under 5 sccm Ar+1 sccm N 2 gas flow. The as-deposited layers have a low wear, showing an increase in hardness after annealing making them suitable as protective layers.

Epitaxial Silicon Oxynitride Layer on a6H−SiC(0001)Surface

Hydrogen-gas etching of a 6H-SiC(0001) surface and subsequent annealing in nitrogen atmosphere leads to the formation of a silicon oxynitride (SiON) epitaxial layer. A quantitative low-energy electron diffraction analysis revealed that the SiON layer has a hetero-double-layer structure: a silicate monolayer on a silicon nitride monolayer via Si-O-Si bridge bonds. There are no dangling bonds in the unit cell, which explains the fact that the structure is robust against air exposure. Scanning tunneling spectroscopy measured on the SiON layer shows a bulk SiO2-like band gap of approximately 9 eV. Great potential of this new epitaxial layer for device applications is described.

Photoactivity of Sol–Gel Derived Nitridated Zn x Ti y O z -Films

Zn x Ti y O z layers were prepared by sol–gel method and nitridated yielding photoactivity in the visible wavelength region. The condensation process of these nanostructures and their subsequent sintering was followed by using XRD-, UV/Vis-, micro-Raman-, FTIR- and thermal analysis measurements. The oxynitride formation during the nitridation process was confirmed by XPS and UV-Vis spectroscopy. The photocatalytical studies of methylene blue (MB) degradation revealed the activity of coloured oxynitride layers under the visible light irradiation. Furthermore, a metachromasy of MB infiltrated within the nanostructured films was observed for the first time. This blue shift in the optical absorption spectrum of MB became even more pronounced during the photodegradation process of this dye.

Crystallization of AlON layers and its effects on the microstructure and hardness of reactively synthesized ZrN/AlON nanomultilayers

By reactively sputtering Zr and Al2O3 targets in a gaseous mixture of Ar and N2, ZrN/AlON nanomultilayers were synthesized to study the crystallization conditions for AlON layers and how they influence the characteristics of multilayers. The composition analysis indicated that some of the oxygen atoms were replaced by nitrogen atoms in Al2O3, leading to the formation of aluminium oxynitride, AlON, during the procedure of the Al2O3 target being sputtered in the gaseous mixture. Further investigations showed that when their thickness was limited to less than 1 nm, amorphous AlON layers were crystallized under the template effects of crystalline ZrN layers, and then coherent interfaces formed as a result. Correspondingly, the multilayers were remarkably strengthened with hardness approaching a maximum of 33 GPa. After the layer thickness of AlON exceeded the critical value of 1 nm, the subsequently deposited AlON grew amorphously and blocked the epitaxial growth of multilayers, accompanied by the decline of hardness. Yet, on the other hand, the integrated hardness of multilayers was not sensitive to the thickness of the ZrN template layers and its value was maintained a bit higher than 30 GPa in a wide range of ZrN layer thickness variations.

Evolution of Structural and Electrical Properties of Plasma Nitrided Silicon Oxynitrides During the Formation Process

In this work the formation of silicon oxynitrides by decoupled plasma nitridation of thin RTO grown silicon oxide films, varying in thickness, and composition was investigated. Non- destructive Cocos measurement techniques were used after each processing step as base oxidation, plasma nitridation and different post nitridation anneals. It was found, that the base oxide thickness strongly influences the interaction of the plasma species with the solid state material, and thereby impacts severely the film properties. A effective model describing the effect of plasma nitridation process on the dielectric material is proposed.

Chemical environment of iron atoms in iron oxynitride films synthesized by reactive magnetron sputtering

An iron oxynitride film was deposited on silicon and glass substrates by magnetron sputtering in an Ar–N2–O2 reactive mixture. Rutherford back-scattering spectrometry was used to determine the film composition (Fe1.06O0.35N0.65). X-ray diffraction revealed the formation of a face-centred cubic (fcc) structure with a lattice parameter close to that of γ‴-FeN. X-ray photoelectron spectroscopy showed the occurrence of Fe–N and Fe–O bonds in the film. The local environment of iron atoms studied by 57Fe Mossbauer spectrometry at both 300 and 77 K gives clear evidence that the Fe1.06O0.35N0.65 is not a mixture of iron oxide and iron nitride phases. Despite a small amount of an iron nitride phase, the main sample consists of an iron oxynitride phase with an NaCl-type structure where oxygen atoms partially substitute for nitrogen atoms, thus indicating the formation of a iron oxynitride with an fcc structure.

Gas/solid reaction during sintering of Si 3N 4 ceramics in an air furnace

Solid/gas reaction during sintering of Si 3N 4 ceramics in an air atmosphere was investigated. The Si 3N 4 specimens were prepared from β-powder with MgO and Al 2O 3 5 wt% each as sintering aids. The oxygen content of the mixtures after milling increased with increasing milling time. The SiO 2 content was found to cause more significant mass loss of the sintered specimens than the sintering temperature. There was also a gradient of the oxygen partial pressure ( P O 2 ) in the crucible during sintering resulting in the formation of silicon oxynitride (Si 2N 2O) on the surfaces of Si 3N 4 specimens in different quantities. The mass loss reaction, amount of mass loss as a function of soaking time and sintering temperature, mass loss difference between the top and the bottom of specimens and the formation of Si 2N 2O are discussed.

Influence of ion nitriding process on the properties of zirconia coating deposited on stainless steel

ZrO2-3 mol % Y2O3-coated AISI 310 stainless steel was nitrided using plasma produced by dc pulsed discharge in a mixture of N2 and H2 at an equilibrium temperature of 450ºC. Profile chemical analyses with GDOS (glow discharge optical spectroscopy) and XRD showed the formation of Nitrogen/Y-ZrO2 solid solution. Nitrogen atoms enter in the zirconia substituting to the oxygen atoms in the network. Although, the nitrogen content measured in zirconia coating is greater than the allowed maximum nitrogen content in doped-zirconia solid solution, the formation of oxynitrides could not be detected. The phase structure was investigated by X-ray diffractometry The mechanical properties were studied by means ultramicrohardness indentation tests. The nitruration improves the mechanical responses of the ZrO2-3 mol% Y2O3 -coated AISI 310 stainless steel.

The initial growth stage in PVT growth of aluminum nitride

AbstractThe main issue in homoepitaxial growth of aluminum nitride (AlN) on native seed substrates is the formation of an aluminum oxynitride (AlON) layer at temperatures between 1850‐1950 °C leading to polycrystalline growth. On the contrary, heteroepitaxial growth of AlN on silicon carbide (SiC) is relatively easy to achieve due to natural formation of a thin molten layer of (Al2OCx) on the seed surface and consequent growth of AlN via the molten buffer layer. Optimization of the seeding process can be achieved by use of ultra‐pure starting material. Another critical issue of AlN growth on SiC is cracking of the grown layer upon cooling as a result of different thermal expansion coefficients. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Synthesis of buried silicon oxynitride layers by ion implantation for silicon-on-insulator (SOI) structures

Silicon oxynitride (Si x O y N z ) buried insulating layers were synthesized by SIMNOX (separation by implanted nitrogen–oxygen) process by 14N + and 16O + ion implantation to high fluence levels 1 × 10 17, 2.5 × 10 17 and 5 × 10 17 ions cm −2 sequentially in the ratio 1:1 at 150 keV into p-type (1 0 0) silicon wafers. The identification of structures and defects in the ion beam synthesized buried layers were carried out by FTIR, XRD and ESR measurements before and after RTA treatments at different temperatures in nitrogen ambient. The FTIR spectra show single broad absorption band in the wavenumber range 1250–600 cm −1 confirming the formation of silicon oxynitride. The integrated absorption band intensity is found to increase with increasing ion fluence and on annealing indicating gradual chemical transformation of the ion implanted layer into silicon oxynitride. The XRD data of the implanted samples show the formation of Si 2N 2O (O) phase of silicon oxynitride. On annealing the samples, SiO 2 (H)/Si 3N 4 (H) phases are also formed in addition to Si 2N 2O (O) phase. The concentration of the formed phases is found to increase with increase in the ion fluence as well as the annealing temperature. The ESR studies both at room temperature and at low temperatures reveal the presence of a defect center associated with silicon dangling bonds. The increase in ion fluence gives rise to small variations in g-values and increase in the spin density. The spin density decreases in general with increasing the annealing temperature.

Crystal growth and superhardness effects of ZrN/AlON nanomultilayers synthesized by reactive magnetron sputtering

Two series of ZrN/AlON nanomultilayers were synthesized by reactively sputtering zirconium and aluminum oxide targets in the gaseous mixture of argon and nitrogen. The thickness of ZrN layers was fixed in one of the series and the thickness of AlON layers in the other. The composition, microstructure and mechanical properties of films were characterized by X-ray energy dispersive spectroscopy, X-ray diffraction, high resolution transmission electron microscopy and nanoindentation. The investigation results indicate that during the process of Al2O3 target sputtering in the mixed atmosphere, part of oxygen atoms in Al2O3 were replaced by nitrogen atoms, leading to the formation of aluminum oxynitride, AlON. Under the influence of the “template effects” of ZrN layers, the AlON layers that used to exist as amorphous under sputtering conditions were forced to crystallize and grew epitaxially with the ZrN layers when the thickness of AlON was limited to less than 0.9 nm. Correspondingly, the hardness of multilayers was remarkably enhanced to its maximum value of 33.0GPa. A further increase in the thickness of AlON layers led to the crystalline AlON layers transforming into amorphous. The epitaxial growth of multilayers was blocked, accompanied by the decline of hardness.

Initial nitride formation at Si∕3C–SiC(100)3×2 interface by oxynitridation

Nitric oxide interaction with 3C–SiC(100)3×2 and Si-3×2∕3C–SiC(100)3×2 surfaces is investigated by synchrotron radiation-based core level photoemission spectroscopy. At 25°C, NO exposures result in oxynitride formation, while annealing at 1000°C removes oxygen leading to a nitride layer. Most interestingly, the results suggest stoichiometric Si3N4 layer formation at Si-3×2∕3C–SiC(100)3×2 interface. This finding is of interest in limiting dopant diffusion and in defect passivation so critical at insulator/SiC interfaces.

Spinel-type gallium oxynitrides attainable at high pressure and high temperature

We study the enthalpy of formation $\ensuremath{\Delta}H$ of spinel-type gallium oxynitrides ($\ensuremath{\gamma}$ galons) as a function of pressure. Formation of the ternary oxynitride from gallia $({\mathrm{Ga}}_{2}{\mathrm{O}}_{3})$ and gallium nitride (GaN) is endothermic at any pressure. $\ensuremath{\Delta}H$ is minimal, however, at the $\ensuremath{\beta}\ensuremath{\rightarrow}\ensuremath{\alpha}$ phase transformation of gallia, which we calculate to occur at 2.6 or $6\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, depending on whether we treat the $d$ elctrons of Ga as core or as valence states. Hence, at this pressure the driving force to form $\ensuremath{\gamma}$-galons is maximal. The positive enthalpy of formation may be compensated by entropy contributions arising from a mixing of O and N within the anion sublattice and of Ga atoms and vacancies on octahedral sites of the cation sublattice. Since with increasing pressure the decomposition of gallium nitride is suppressed, we propose the synthesis of ternary spinel-type gallium oxynitrides at high temperature and/or high pressure conditions.

Characterization of Ultra Thin Oxynitride Formed by Radical Nitridation with Slot Plane Antenna Plasma

We investigated the plasma nitridation mechanisms for an ultra-thin gate oxynitride (SiON) formation to extend the downscaling limit of equivalent oxide thickness (EOT). Using the slot plane antenna (SPA) plasma nitridation system, excellent gate SiON properties were obtained with low gate leakage and good carrier mobility down to less than 12 Å. From electrical and physical analysis results, the nitridation mechanism was discussed, which suggested that a control of oxygen partial pressure is important to achieve EOT reduction. A low electron temperature (Te) process under high-pressure condition leads to improved Gm and NBTI performance, which indicates that the reduction of a plasma damage under nitridation processes improve the performance and reliability of ultra thin SiON film. With optimized nitridation processes, the mobility degradation of nMOSFET is only 8% at EOT=11 Å. The NBTI reliability of pMOSFET is improved by more than 1 order compared with a low-pressure, high Te condition.

Formation of niobium oxynitrides by rapid thermal processing (RTP)

The potential of rapid thermal processing (RTP) for the preparation of thin films of niobium oxynitrides was investigated. The 200 and 500 nm niobium films were deposited via sputtering on oxidized silicon(1 0 0)- and on sapphire(1 −1 0 2)-substrates. At first, oxidation of niobium films in molecular oxygen and then nitridation in ammonia using an RTP-system was performed. The films were characterized before and after the oxidation and nitridation processes by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). The influence of the two different substrates, amorphous SiO 2 and single crystalline sapphire on the reactivity of the niobium films was studied in dependence of temperature, time of reaction and film thickness. The existence of niobium oxynitride formation was verified for some of the films. In some of the experiments, crack formation in the films or even delamination of the Nb-films from the substrates was observed.

The Use of Trimethylaluminum for Producing Surface Layers by the PACVD Method

The paper presents the use of trimethylaluminum in PACVD method to obtain the surface layers like alumina or aluminum nitride on Inconel nickel alloy. The glow discharge nitriding at a temperature of 750°C leads to the formation of aluminum oxynitride in the layer, whereas annealing in argon plasma at a temperature of 1050°C – to the formation of nickel and aluminum based intermetallic phases of the NiAl or Ni3Al type with aluminum oxide present within the outer zone of the coating. The presence of the surface layer of the Al2O3+NiAl+Ni3Al type formed on nickel alloys may be significant from the point of view of the applications that require a high heat resistance.

Formation of Oxynitride as the Photocatalytic Enhancing Site in Nitrogen‐Doped Titania Nanocatalysts: Comparison to a Commercial Nanopowder

AbstractA nitrogen‐doped TiO2 nanocolloid has been successfully prepared and its properties compared with the commercially available TiO2 nanomaterial, Degussa P25. Several characterization techniques, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), Fourier transform infrared (FT‐IR) spectroscopy, Raman scattering, and UV‐visible reflectance spectra, are combined in order to determine the crystal phase and grain size, shape, degree of nitrogen incorporation, and nature of the resultant oxynitride chemical bonding on the surface and in the bulk. The high relative photocatalytic activity of the nitrogen doped‐TiO2 nanocolloid is evaluated through a study of the decomposition of methylene blue under visible light excitation. The ease and degree of substitutional‐insertional nitrogen doping is held accountable for the significant increase in photocatalytic activity in the porous nanocolloid versus the nitrided commercial nanopowder. It is suggested that the nitrogen incorporation produces an NO bonding region as evidenced by the resulting XPS spectrum.

Formation of spinel-type gallium oxynitrides: a density-functional study of binary and ternary phases in the system Ga–O–N

We perform first-principles calculations to investigate the structure of spinel-type gallium oxynitrides (γ-galons) as well as their formation from and relative stability to the binary phases gallium oxide (Ga2O3) and gallium nitride (GaN). Besides the ideal cubic γ-galon Ga3O3N with a content of 50 mol% GaN, we study approximants of defective γ-galons corresponding to 36 mol% and 17 mol% GaN within the Constant-Anion-Model. Enthalpies of formation indicate that at ambient pressure the ternary compounds are unfavorable relative to a phase assemblage of monoclinic β-Ga2O3 and wurtzite GaN. A comparison to spinel-type aluminium oxynitrides γ-alons is made. We find the difficulties in synthesizing γ-galons to be related to the low energy of the ground state structure of monoclinic β-Ga2O3.