Oxygen Depth Profiles Research Articles

Rutile formation and oxygen diffusion in oxygen PIII-treated titanium

Using oxygen plasma immersion ion implantation (PIII) into pure titanium with 30-kV pulses at different temperatures between 265 and 550°C, pure, stoichiometric rutile without oxygen vacancies was obtained with Raman spectroscopy. Ion beam analysis — elastic recoil detection analysis (ERDA) and Rutherford backscattering spectroscopy (RBS) — was employed to determine the oxygen depth profiles. A thermally activated growth of this stoichiometric rutile layer is observed with a sharp interface to the bulk titanium. No broadening of the interface beyond 15–20 nm, the depth resolution of the profiling methods, accompanies this process. In contrast, at temperatures above 400°C a deep tail of oxygen diffusing into the titanium is found, reaching more than 0.5 μm within 1 h. This oxygen depth distribution can be described by a complementary error function. Again, the diffusion constant and the activation energy were derived from the measurements. For the second process a higher activation energy of 0.85 eV, compared with 0.5–0.6 eV for the bulk growth of TiO 2 is found.

Oxidation of Si(001) Surfaces Studied by High-Resolution Rutherford Backscattering Spectroscopy

The feasibility of high-resolution Rutherford backscattering spectroscopy (HRBS) to study the initial stage of Si(001) oxidation is examined. It is shown that HRBS provides oxygen depth profiling with depth resolution at an atomic level. After oxidation of Si(001) at room temperature under 2 ×10-6 Torr oxygen partial pressure for 20 min, the coverage of oxygen was determined to be 1.2 ±0.3 ML.

Oxygen migration during epitaxial regrowth in Cs+-irradiated α-quartz investigated by means of nuclear reaction analysis

The migration of oxygen in ion-beam-amorphized c-SiO2 (α-quartz) was investigated by means of nuclear reaction analysis using the resonant reaction O18(p,α)15N for oxygen depth profiling. Only very small amounts of oxygen were observed to diffuse in crystalline or in Xe+-ion beam-amorphized α-quartz after high-temperature annealing. However, a dramatic migration of oxygen occurs in Cs+-implanted α-quartz in the same temperature range (600–900 °C), where Cs diffuses out of the amorphized layer and epitaxial recrystallization occurs. These results point out to a strong correlation of all these processes. A mechanism to explain the observed indiffusion of O18 is proposed and is related to the Cs migration and the topological modification to achieve epitaxial regrowth of the SiO2 matrix.

Characterization of ultra thin oxynitrides: A general approach

The determination of nitrogen depth profiles in thin oxynitride layers (1.5–3 nm) becomes more and more important in microelectronics. The goal of this paper is to investigate a methodology for the characterization of thin oxynitride layers with the aim to establish in a quantitative manner the layer thickness, N-content and detailed N-depth profile. For this study ultra thin oxynitride films of 2.5 nm on Si were grown by oxygen O 2 annealing of Si followed by a NO annealing. The global film characteristics were measured using spectroscopic ellipsometry (SE) (thickness), atomic force microscopy (AFM) for roughness and X-ray photoelectron spectroscopy (XPS) for total O- and N-content. Depth profiles of oxygen, silicon and nitrogen were obtained using (low energy) secondary ion mass spectroscopy (SIMS) and time of flight (TOF)-SIMS, high resolution-Rutherford backscattering (H-RBS) (magnetic sector and TOF) and high resolution-elastic recoil detection (H-ERD). A comparison of the results obtained with the different techniques is presented and discussed.

The influence of the oxygen partial pressure on the ion nitriding of aluminium – An investigation by means of real time elastic recoil detection analysis

Aluminium is known to be a difficult candidate for successful nitriding. It exhibits a dense native surface oxide layer that acts as a barrier for diffusional nitrogen transport. To investigate the influence of the oxygen partial pressure, samples of pure polycrystalline Al were ion nitrided at different oxygen partial pressures from a hot filament ion source. Before and during the nitriding process depth profiling of nitrogen and oxygen has been performed by real time elastic recoil detection analysis. The oxygen partial pressure plays a crucial role for the evolution of the surface oxide layer and thus for the nitriding result. If the surface oxide layer is removed an AlN-layer grows. The evolution of the oxide layer is compared to semi-quantitative considerations on the interplay of sputtering and oxidation. A criteria for the removal of the surface oxide layer is given.

Depth profiling: RBS versus energy-dispersive X-ray imaging using scanning transmission electron microscopy

Rutherford backscattering spectrometry (RBS) is known to be one of the techniques ideal for analysis of thin films. Elemental concentrations of matrix components and impurities can be investigated as well as depth profiles of almost each element of the periodic table. Best of all, RBS has both a high sensitivity and a high depth resolution, and is a non-destructive analysis technique that does not require specific sample preparation. Solid-state samples are mounted without preparation inside a high-vacuum analysis chamber. However, depth-related interpretation of elemental depth profiles requires the material density of the specimen and stopping power values to be taken into consideration. In many cases, these parameters can be estimated with sufficient precision. However, the assumed density can be inaccurate for depth scales in the nanometer range. For example, in the case of Ge nanoclusters in 500 nm thick SiO 2 layers, uncertainty is related to the actual position of a very thin Ge nanocluster band. Energy-dispersive X-ray emission (EDX) spectroscopy, using a high-resolution scanning transmission electron microscope (STEM) can assist in removing this uncertainty. By preparing a thin section of the specimen, EDX can be used to identify the position of the Ge nanocluster band very precisely, by correlating the Ge profile with the depth profiles of silicon and oxygen. However, extraction of the concentration profiles from STEM–EDX spectra is in general not straightforward. Therefore, a combination of the two very different analysis techniques is often the best and only successful way to extract high-resolution concentration profiles.

Modeling of aerobic biodegradation and oxygen consumption in benthic sediments

A brief overview of the existing chemical and biological models of biodegradation in porous media is given. A revised biological model of aerobic degradation of organic matter in benthic sediments is developed. The model is based on steady state balance equations for microbial mass, organic matter, and oxygen. The biomass balance equation involves a logistic trophic function (instead of the classical Malthusian one) describing the self‐regulation of microbial abundance. One of the corollaries of the model is the dependence of the decay rate upon the organic matter content S in the form dS/dt ∝ S2/(S + Ks)2 (where Ks is a constant) that implies two extreme cases: dS/dt is independent of S at small Ks (refractory organics) and dS/dt ∝S2 at large Ks (labile organics), instead of the commonly used law dS/dt ∝ S. The oxygen consumption rate J is expressed through the oxygen concentration O0 in the overlying water and three generalized parameters. This function demonstrates the effect of the plateau at large O0. The dependence J(O0) is calibrated for the three experimental systems of the literature, two of which have high oxygen consumption rates and one low. For the latter, the model parameters are estimated and their correspondence to the evidence available is discussed. Depth profiles of oxygen, organic matter, and biomass are computed and the aerobic zone thickness is determined.

Water uptake of quartz investigated by means of ion-beam analysis

The diffusion of water into quartz was studied by measuring depth profiles of hydrogen and oxygen in hydrothermally treated samples using ion-beam analysis methods. Diffusion data were obtained in the temperature range 60 to 200 °C. It was found that the initial H content of the individual quartz specimen plays a crucial role for the diffusion rate, which also depends on the orientation of the sample surface relative to the quartz c-axis. External factors which possibly influence the diffusion data were examined. Hydrogen depth profiles measured on a prehistoric quartz artifact were found to be compatible with an extrapolation of the diffusion data to ambient temperature.

Electrolytic conduction of silver metaphosphate glass until dielectric breakdown

Ac/dc bias was applied to gold- or silver-electroded AgPO3 glass samples at ∼150 °C. Dielectric breakdown took place with bias fields of ∼700 V/cm. Depth profiles of silver, gold, oxygen, and phosphorus were measured from the electrode surfaces by x-ray photoelectron spectroscopy. Electrolytic conduction of silver and others and field-induced injection of gold ions into glass from the gold anode were found.

Growth/dissolution model for oxygen precipitation based on the kinetics of phase transformations

A model is presented for the growth and dissolution of oxygen precipitates in Czochralski silicon during heat treatment. Growth and dissolution rates are newly derived and inserted into a set of chemical rate equations and a Fokker–Planck equation. It can calculate the size distribution of the oxygen precipitates and oxygen concentration profile without calculation of the interfacial concentrations at the interface of Si matrix and precipitates. It accounts for the oxidizing ambient effect, the solubility enhancement effect of oxygen, and the surface recombination and generation of point defects. The formation of stacking faults is also taken into account. This approach allows one to calculate more accurately the residual oxygen depth profile and the density distribution of oxygen precipitates which can be measured experimentally. By comparing the simulated results with experimental ones, it is proved that this model can be used to estimate the depth profile and the defect densities under inert conditions and oxidation conditions.

Untersuchung der Randoxidation nach dem Gasaufkohlen in mit Restsauerstoff verunreinigten Stickstoff-/Methanolatmosphären

Nitrogen, which is generated using the membrane or PSA method, contains caused by the generation process higher oxygen contaminations as cryogenic produced nitrogen. The investigations presented in this paper were done in order to find out if there is an influence of this remaining oxygen on the heat-treatment results particularly on the internal oxidation after carburizing. The tests were done on four different steel grades with a chromium content between 0,5-5,1% and a manganese content between 0,4 and 1,2%. The applied carburizing atmosphere was based on a 60 vol. % methanol and 40 vol. % nitrogen mixture. For the treatments with increased oxygen content, oxygen in the order of 0,5 and 1,0% was added to the nitrogen. The quantitative characterization of the internal oxidation was done by help of a scanning electron microscope and an image analysis system. The influence of the oxygen content on the microstructure and the microhardness was determined. Moreover, carbon and oxygen depth profiles were measured using the optical glow discharge spectroscopy and the results were compared with the ones from the image analysis system.

High Sensitivity Determination of Oxygen Distribution in Thin Epitaxial Silicon Films by Carbon Implantation‐Photoluminescence Measurement

A method was developed to measure low level oxygen concentration in thin epitaxial silicon film (epi film) by measuring photoluminescence (PL) intensity of an oxygen‐carbon complex (C center) formed in silicon crystal by carbon implantation (energy: 20 keV). A calibration curve between the PL intensity of the C center and the oxygen concentration of standard samples for each carbon implantation fluence was obtained. In order to measure the oxygen distribution of the depth direction in an epi sample with the epi thickness of 1 μm, many epi samples were etched to appropriate depths prior to the carbon implantation. The calibration curve established above was applied to the PL intensity of the etched and implanted epi sample, and the relationship between the oxygen concentration in the epi sample and the depth from the epi‐surface was obtained with the sensitivity level of . The concentration of oxygen, diffused from the substrate, increased monotonously from the epi layer to the substrate without any abrupt change at the interface between them. The oxygen depth profile of the whole region (epi layer and substrate) could not be fitted by a simple diffusion function such as a complementary error function. © 1999 The Electrochemical Society. All rights reserved.

Effects of Annealing on Oxygen Depth Profiles and Chemical Etching Rates of Thermally Grown Silicon Oxides

Effects of annealing on oxygen depth profiles and chemical etching rates of thermally grown silicon oxides are investigated in order to characterize the intermediate layer, adjacent to the oxide/silicon interface. We found that the oxygen Auger signal intensity for the samples grown at 800 and 900°C with a thickness of 11 nm, increases in the region that is several nanometers thick, adjacent to the oxide/silicon interface. Furthermore, the chemical etching rates of the samples grown at 800 and 900°C decrease in just about the same region, adjacent to the interface. However, we found no intermediate layer in the samples grown at 1000°C, or annealed at 1000°C. These experimental results indicate the existence of an intermediate layer that has a higher oxygen content, and dissolves slower in an etching solution, than the bulk oxide. The intermediate layer is believed to contain highly dense quasi‐stable silica that is compacted by the compression stress Annealing at 1000°C must result in a transformation of the intermediate layer to a more stable structure with a lower density.

Proton non-Rutherford backscattering study of oxidation kinetics in Cu and Fe sulphides

Non-Rutherford backscattering spectrometry (NBS) with 2.4 MeV protons was performed for depth profiling of oxygen in three species of copper and iron sulphides – pyrite, chalcopyrite and bornite – on both altered and fresh surfaces. The tarnished surfaces were obtained by bathing samples in H 2O 2 (35% vol.) for 100 and 1000 s. The spectra collected were compared to simulations to extract quantitative data on oxygen depth distributions for the different bathing times. The measurements have shown that the kinetics of oxidation has completely different patterns in the three investigated minerals.

Oxygen depth profiling in [formula omitted] prepared by sol-gel method using 16O(α, α) 16O resonant backscattering

In order to find the optimum conditions to obtain films with high photocatalytic property by sol-gel method, depth profiling of oxygen in TiO x film deposited on SiO 2 was carried out using resonant backscattering of 3.045 MeV He ions by the nuclear reaction of 16O(α, α) 16O. Depth profiling of hydrogen in the TiO x film was also conducted using elastic recoil detection analysis (ERDA). For the depth profiling by the resonant backscattering analysis, it is necessary to change the incident energy of He ions from about 3.03 to 3.1 MeV in steps of less than 10 keV. In our analyzing system, the ion beam energy of He ++ was scanned by changing a bias voltage supplied to the target holder up to +30 kV without changing the accelerator terminal voltage. The effect of the bias voltage supplied on the sample holder on the energy and the yield of the oxygen peak relative to the titanium and the silicon signal were investigated. The automatic analysis system and the analyzed results are presented.

Nuclear reaction microanalysis: A key for the study of uranium dioxide corrosion mechanisms

Deuteron and/or helium-3 ion microbeams have been used to determine the near-surface composition of uranium dioxide leached in a granitic groundwater and particularly the oxygen depth profile. The use of a ΔE− E telescope allows us to exploit both the backscattering part and the nuclear reaction part of the energy spectra so that the uranium depth profile and the surface O/U ratio of the oxide can be infered. Nuclear reaction investigation has been completed with X-ray photoelectron spectroscopy (XPS) measurements in order to derive simple alteration models.

Assessing organic matter mineralization, degradability and mixing rate in an ocean margin sediment (Northeast Atlantic) by diagenetic modeling

We test whether organic matter degradability, mixing activity, and total sediment mineralization can be estimated by inversion of a coupled nonlinear numerical steady-state diagenetic model. We use a single data set comprising oxygen, nitrate, ammonium and organic carbon versus depth profiles from a slope station in the Goban Spur area (1034 m, Northeast Atlantic). Based on an extensive sensitivity analysis, it appears that (1) when using all data, the total mineralization rates can be determined with reasonable precision; bioturbation and degradability are less well constrained and (2) total mineralization rates can be determined based on nitrate and oxygen profiles only; estimates of organic matter mixing rates and degradability are refined when including the solid phase organic carbon profile. The bulk mixing rates obtained for organic carbon are one order of magnitude higher than mixing rates previously estimated from Pb-210 profiles, lending validity to the hypothesis that organic particles are mixed faster than inert particles. The degradability of the organic carbon prior to its incorporation in the sediment is in the order of 10-30 yr(-1), indicating that mineralization in this slope station of the Goban Spur area is fueled mainly by freshly deposited organic matter. [KEYWORDS: Benthic oxygen-demand; deep-sea sediments; marine-sediments; hemipelagic sediments; nutrient diagenesis; equatorial pacific; water interface; carbon; bioturbation; nitrogen]

High resolution depth profiling in silicon oxynitride films using narrow nuclear reaction resonances

We report here on the determination of depth profiles of oxygen and nitrogen with nanometer resolution in silicon oxynitride films with thicknesses below 3 nm. We have studied oxynitride films grown by rapid thermal processing of Si (0 0 1) wafers in various Nitric Oxide (NO) atmospheres. Angle Resolved X-Ray Photoelectron Spectroscopy (ARXPS) analyses were carried out to determine the chemical composition of the films as well as the spatial distribution of the chemical bonds. The nuclear depth profiling method uses narrow, isolated resonances found in the cross section of the nuclear reactions 18O(p,α) 15N at 152 keV and 15N(p,αγ) 12C at 429 keV. The excitation curves of the nuclear reactions in the neighbourhood of the resonance energies can be used to determine the concentration versus depth profiles by means of SPACES, a personal computer implementation of the stochastic theory of energy loss. We discuss aspects of the simulation of excitation curves and the effect of NO pressure on the structure of the oxynitride film.

Effect of oxygen implantation upon the corrosion resistance of the OT-4-0 titanium alloy

The properties of the surface layer on the OT-4-0 titanium alloy after oxygen implantation were examined. Polished samples were implanted with doses of 5 × 10 16 and 1 × 10 17 O + cm −2. The O + ion energy was 50 keV. Transmission electron microscopy has been used to investigate the microstructure of the implanted layers formed on the OT-4-0. It was found that the implanted layers are nanocrystalline rutile (TiO 2). Depth profiles of oxygen and titanium were investigated by SIMS and corrosion resistance was analysed by electrochemical techniques. The results indicate that the oxygen implantation increases the corrosion resistance of the OT-4-0 titanium alloy.

Ionic implantation at low energy: application to the shallow junction accomplishment and surface functionalization

The proposed work deals with rapid thermal processing of ionic boron ( 11B +) and boron difluoride (BF 2 +), implanted in phosphorusdoped Cz-(100) silicon substrates through protecting oxide films, under different technological parameters. After implantation, the samples were rapidly thermally annealed at temperatures ranging from 900 to 1100 °C, in argon ambient gas, for different annealing durations. The rapid thermal annealings (RTAs) are carried out also, for some samples, after oxide mask removal. The total boron, fluorine as well as oxygen concentrations versus depth profiles, before and after annealing steps, in the SiO 2/Cz-(100) silicon systems were determined using secondary ion mass spectrometry (SIMS). Using a background concentration, the junction depth in the substrate has been investigated under different annealing experimental conditions. The kinetic diffusion process of implanted boron into oxide and monocrystalline silicon during rapid thermal treatments has also been investigated. The reported results show that boron diffusion in the BF 2 + case is widely reduced during rapid thermal treatments. Discussions of this are based on the effect of both knocked-on oxygen and fluorine on the boron diffusion kinetics.