Doses Of Nitrogen Ions Research Articles

RIBAD Deposition of TiN on Magnesium Alloy

TiN coatings were produced by depositing a series of Ti layers and subsequently ion implanting 80 keV nitrogen ions. TRIDYN FZR software simulation was used to estimate the maximum Ti layer thickness which could be successfully transformed to TiN by ion implantation. The chemical profile of these coatings was achieved by conducting a series of EDS measurements across coatings, sectioned at shallow angles. It was found that the structure of the RIBAD TiN films produced changes significantly with the implanted nitrogen ion dose. Their hardness and wear resistance were found to increase rapidly as the post implantation time was increased up to 230 minutes, reaching a maximum of 27GPa and 2.5x10-12 mm3m-1N-1 respectively. On the other hand, the electrochemical corrosion resistance of TiN coated magnesium substrate was inferior to that of the untreated substrate material. The results suggest that the coating developed is attractive as a topcoat of a duplex coating; having as underlay a corrosion protective film. In a separate study, it has been shown that such coatings could be ion beam sputtered titania or alumina.

Load Dependence of Nanohardness in Nitrogen Ion Implanted Ti6Al4V Alloy and Fractal Characterization

Abstract Three different nitrogen ion doses were implanted into a Ti6Al4V alloy to improve its mechanical surface properties for the application of artificial joints. The titanium nitride phase and nitrogen element distribution profile were characterized with X-ray photoelectron spectroscopy (XPS). Nano-indentation tests were carried out on the surface of the Ti6Al4V alloy and implanted samples on a large scale of applied loads. The XPS analysis results indicate that nitrogen diffuses into the titanium alloy and forms a hard TiN layer on the Ti6Al4V alloy. The nanohardness results reveal that nitrogen ion implantation effectively enhances the surface hardness of Ti6Al4V. In addition, the nanohardness clearly reveals load dependence over a large segment of the applied loads. Thus a concept of nanohardness fractal dimension is first proposed and the dual fractal model can effectively describe nonlinear deformation in indentation areas on the Ti6Al4V surface. The fractal dimension shows a decreased trend in two regions of applied loads, indicating a decrease of the self-similarity complexity in surface indentation owing to an increase in nanohardness after nitrogen ion implantation.

On the Study of the Atomic Structures of Nitrogen-Ion-Implanted InP

Nitrogen ions at doses of 1 ◊ 10 13 ‐ 1 ◊ 10 15 cm 2 have been implanted in semi-insulating (SI) InP (100) single-crystal substrates. The surface topography of as-grown and implanted samples has been investigated using atomic force microscopy (AFM). The as-grown InP surface has minimum roughness and appears to be smooth. Angstrom-level pits-type defects are seen on the InP surface after the implantation. Root-mean-square roughness values measured for the as-grown and the implanted InP samples. The surface roughness increased with increasing the nitrogen-ion dose monotonically up to 5 ◊ 10 14 cm 2 and decreased at a dose of 1 ◊ 10 15 cm 2 the increase in the roughness was due to implantation-induced damages, and the decrease at higher dose 10 15 cm 2 might have been be due to plastic deformation on the surface associated with a surface amorphisation. Post-implantation annealing smoothened the surface. Roughness values decreased relative to the implanted samples up to a dose 5 ◊ 10 14 cm 2 , which indicates that the defects were partially annealed. At a higher dose of 10 15 cm 2 , there was no change in roughness value in spite of annealing. This indicates that the InP surface had been plastically deformed leading to amorphization at higher dose. Further, Raman characterization of these implanted samples clearly supports the surface amorphization at higher doses.

Synthesis of GaN phase by ion implantation

GaN phase is synthesized using systemic implantation of nitrogen ions of multiple energies (290, 130 and 50 keV) into Zn-doped GaAs (1 0 0) at room temperature and subsequent annealing at 850 °C for 30 min in Ar + H 2 atmosphere. The implanted doses of nitrogen ions are 5 × 10 16 and 1 × 10 17 ions-cm −2. Glancing angle X-ray diffraction studies show that hexagonal phase of GaN were formed. The photoluminescence studies show the emission from the band edge as well as from point defects.

Clusters of DNA Double-Strand Breaks Induced by Different Doses of Nitrogen Ions for Various LETs: Experimental Measurements and Theoretical Analyses

The yields and clustering of DNA double-strand breaks (DSBs) were investigated in normal human skin fibroblasts exposed to gamma rays or to a wide range of doses of nitrogen ions with various linear energy transfers (LETs). Data obtained by pulsed-field gel electrophoresis on the dose and LET dependence of DNA fragmentation were analyzed with the randomly located clusters (RLC) formalism. The formalism considers stochastic clustering of DSBs along a chromosome due to chromatin structure, particle track structure, and multitrack action. The relative biological effectiveness (RBE) for the total DSB yield did not depend strongly on LET, but particles with higher LET produced higher fractions of small DNA fragments, corresponding in the formalism to an increase in the average number of DSBs per DSB cluster. The results are consistent with the idea that DSB clustering along chromosomes is what leads to large RBEs of high-LET radiations for major biological end points. At a given dose, large fragments are less affected by the variability in LET than small fragments, suggesting that the two free ends in large fragments are often produced by two different tracks. The formalism successfully described an extra increase in small DNA fragments as dose increases and a related decrease in large fragments, mainly due to interlacing of DSB clusters produced along a chromosome by different tracks, since interlacing cuts larger DNA fragments into smaller ones.

A study on the Surface Properties of Nitrogen Implanted H13 Steel by Plasma Immersion Ion Implantation

The near surface of the H13 steel was implanted by using Plasma immersion ion implantation (PIII) system at constant bias voltage of −20 kV with varying nitrogen (N+ ) ion dose (3, 6, 9, 12, 15×1017 ions/cm2 ). The surface properties of the N+ ion implanted steel were investigated by measuring the microhardness, wear loss and friction coefficient. As increasing N+ ion dose (12×1017 ions/cm2), both wear property and surface hardness were increased. However, these properties were decreased as the incident ion dose increased over 12×1017 ions/cm2. The elemental depth profile and surface roughness were obtained with X-ray photoelectron spectroscopy (XPS) and surface roughness tester, respectively.

The effect of nitrogen ion implantation on the structural, optical and electrical properties of ZnSe thin films

Zinc selenide thin films were deposited onto well-cleaned glass and silicon substrates using the vacuum evaporation technique under a vacuum of 3 × 10−5 Torr. These films were implanted with mass-analysed 75 keV N+ ions at different doses ranging from 1014 to 1016 ions cm−2. The composition, microstructure, surface roughness, optical bandgap and electrical properties of the as-deposited and nitrogen-implanted films were studied by Rutherford backscattering (RBS), grazing incidence x-ray diffraction (GIXRD), atomic force microscopy (AFM), Raman scattering, optical transmittance and I–V measurements. The RBS analysis indicates that the composition of the as-deposited and nitrogen-implanted films is nearly stoichiometric. The thickness of the as-deposited film is calculated as 230 nm. The structure of the as-deposited and nitrogen-implanted thin films is cubic. In the AFM analysis, the surface roughness is found to increase with an increasing dose of nitrogen ions. In the optical studies, the optical bandgap value decreases with increase of the N+ dose. The prepared device exhibits a very good response in the visible region.

Experimental study of dropwise condensation on plasma-ion implanted stainless steel tubes

Plasma-ion implantation was used to achieve stable dropwise condensation of saturated steam on stainless steel tubes. For the investigation of the efficiency of plasma-ion implantation regarding the condensation process a condenser was constructed in order to measure the heat flux density q ˙ and the heat transfer coefficient h c for the condensation of steam on the outside surface of a single horizontal tube. For tubes implanted with a nitrogen ion dose of 10 16 cm −2, the heat transfer coefficient h c was found to be larger, by a factor of 3.2, in comparison to values theoretically calculated by the corrected Nusselt film theory. The heat flux density q ˙ and the heat transfer coefficient h c were found to increase with increasing ion dose and steam pressure. The heat transfer coefficient decreases with increasing surface subcooling as it has been found in former work for dropwise condensation on ion implanted vertical plates.

Effects of nitrogen implantation on lifetime of cutting tools made of SK5M tool steel

Nearly 100 cutting tools made of SK5M tool steel (DIN S 6-5-2-5) were implanted with 80 keV nitrogen ions at fluences ranging from 1 to 5×10 17 cm −2. The tool lifetimes were examined during routine shaping of roller-bearing rings made of LH15 bearing steel on the production line of an industrial roller-bearing manufacturer. It was found that the lifetime-dose dependence could be described by a quadratic expression and for an optimum nitrogen ion dose, lifetime was found to increase by a factor of 1.6. Measurements were made of nitrogen profiles samples of SK5M steel by glow discharge optical spectroscopy (GDOES). The phase composition of the implanted layer was studied by conversion electron Mössbauer spectroscopy (CEMS) and micro- and nano-hardness measurements were also performed. Good agreement was found between the experimental results and the theoretically predicted profiles of implanted nitrogen with sputtering taken into account. Hardness increments associated with implantation were moderate. It has been concluded that the increased wear resistance can be correlated with the content of Fe 3− x N ( x = 0.33 and 0.5) phases in the implanted layer.

Electrical properties of films grown on W and Mo substrates by titanium ion implantation in nitrogen atmosphere

Films consisting of alternating nitride and oxide layers differing in phase composition and structure are grown on polycrystalline tungsten and molybdenum substrates by ion implantation. The resistivity and thermoelectric power of the films are measured as functions of temperature, and the temperature coefficient of their resistance is determined. The phase composition and electrical properties of the films are shown to be governed by the nitrogen-ion dose delivered to the titanium target.

A study of interface and adhesion of c-BN film on Si(100) modified by nitrogen plasma based ion implantation technique

Cubic boron nitride (c-BN) films were deposited on Si substrate with poor adhesion using magnetically enhanced active reaction evaporation (ME-ARE). An attempt has been made to enhance the adhesion strength between c-BN film and substrate by nitrogen plasma based ion implantation (PBII) into c-BN film. Nitrogen ion doses range from 5×10 16 to 1×10 17 ions cm −2 at an implant voltage of 50 kV. The nitrogen ion implanted c-BN films were analyzed using FTIR, scratch test, and XPS to investigate the change of structure, adhesion strength of c-BN film, and interfacial mixing between the initial turbostratic BN (t-BN) film layer and substrate caused by nitrogen ion implantation. FTIR spectra showed little change of c-BN phase content in the films under the above implantation conditions but XPS depth elemental profile of N + -implanted boron nitride films displayed a mixed layer consisting of elements from film and substrate formed at interface. A highly optimized dynamic Monte Carlo program TAMIX was used to simulate the PBII process in a good agreement with above measured depth elemental profile. The scratch test showed that the adhesion strength evaluated in terms of the critical load of N + -implanted c-BN film was 1.4 times higher than that of as deposited c-BM film.

A study of interface and adhesion of c-BN film on Si(1 0 0) modified by nitrogen plasma based ion implantation technique

Cubic boron nitride (c-BN) films were deposited on Si substrate with poor adhesion using magnetically enhanced active reaction evaporation (ME-ARE). An attempt has been made to enhance the adhesion strength between c-BN film and substrate by nitrogen plasma based ion implantation (PBII) into c-BN film. Nitrogen ion doses range from 5×10 16 to 1×10 17 ions cm −2 at an implant voltage of 50 kV. The nitrogen ion implanted c-BN films were analyzed using FTIR, scratch test, and XPS to investigate the change of structure, adhesion strength of c-BN film, and interfacial mixing between the initial turbostratic BN (t-BN) film layer and substrate caused by nitrogen ion implantation. FTIR spectra showed little change of c-BN phase content in the films under the above implantation conditions but XPS depth elemental profile of N +-implanted boron nitride films displayed a mixed layer consisting of elements from film and substrate formed at interface. A highly optimized dynamic Monte Carlo program TAMIX was used to simulate the PBII process in a good agreement with above measured depth elemental profile. The scratch test showed that the adhesion strength evaluated in terms of the critical load of N +-implanted c-BN film was 1.4 times higher than that of as deposited c-BM film.

XPS studies on silicon carbonitride films prepared by sequential implantation of nitrogen and carbon into silicon

Silicon carbonitride films are synthesized by sequential implantation of nitrogen and carbon into silicon. The evolution of the chemical bonding states between silicon, nitrogen and carbon is investigated as a function of implantation sequence and ion dose using X-ray photoelectron spectroscopy. Nitrogen ion implantation into silicon saturates upon the formation of a stoichiometric silicon nitride film. Successive implantation of carbon into this film leads to the formation of a complex of silicon carbonitride and pure carbon. The formation of CN bond is insignificant. Carbon ion implantation into silicon leads to a continuous increase in carbon concentration till the formation of a nearly pure carbon film at the surface. Successive implantation of nitrogen into this film first forms a film dominated by CC and CN bonds. With increase in nitrogen ion dose, it evolves into a silicon nitride film containing a small fraction of CC, CN and CSi bonds. The formation of CN bond is due to the existence of large amount of pure carbon.

Dose- and energy-dependent behaviour of silicon nitride films produced by plasma immersion ion implantation

Schottky devices having guard ring structures were fabricated with conventional silicon processing technology. Nitrogen ions were implanted in contact area silicon at three doses corresponding to low, moderate and high regime. The implantation was carried out employing Plasma Immersion Ion Implantation (PIII) technique at two pulse voltages, i.e. −10 and −20 kV. The dose of nitrogen ions was controlled by changing the frequency of applied pulses. The samples were metallized and patterned to make Schottky contacts. Each sample was divided into two parts and one set was annealed in forming gas ambient at 450 °C. Current–voltage characteristics of the samples showed the change in barrier height. High dose samples at 10 kV pulse energy were found to exhibit characteristics similar to that of metal-insulator-semiconductor (MIS) structures. Thermal annealing in forming gas was effective to eliminate the defects in the p-type silicon samples to a greater extent and to a lesser extent, in n-type samples.

Effect of nitrogen ion implantation on the microstructural transformation of boron film

The structural transformation by nitrogen ion implantation into boron film as a function of film thickness, implant voltage and nitrogen ion dose was systematically investigated. Boron films were deposited on single crystal Si substrates using the electron beam evaporation of pure metallic boron, the thickness being 200, 500, 1000 and 2000 Å, respectively. The films were then nitrogen ion-implanted at 25-, 50- and 75-kV implant voltages applied to substrate, respectively, for a fixed nitrogen ion dose of 3×10 17 cm −2, and at 1×10 17, 2×10 17 and 3×10 17 cm −2 nitrogen ion doses, respectively, for a fixed implant voltage of 50 kV. The nitrogen ion-implanted boron films were characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). XPS results showed that the nitrogen ion-implanted boron films were nitrogen-deficient. Boron exists in the form of both metallic boron and boron nitride as indicated by XPS B1s bands. FT-IR spectra revealed that amorphous boron nitride (a-BN) or hexagonal boron nitride (h-BN) formed during nitrogen ion implantation into boron films. As implant voltage and nitrogen ion dose increased, amorphous BN was initially formed, while h-BN occurred at greater implant voltage and nitrogen ion dose. The thinner film led to the formation of h-BN at a relatively low implant voltage and nitrogen ion dose.

Ability of a gridless ion source to functionalize polypropylene surfaces by low-energy (60–100 eV) nitrogen ion bombardment. Effects of ageing in air and in water

Polymer surface treatments are of great importance for various industrial applications that can range from food packaging or car bumper painting to biocompatible implants. For such applications, plasma or corona discharges are well known and used “on-line” in polymer plants to incorporate new chemical functions at polymer surfaces. The aim of this work is to investigate the ability of a simple ion source to functionalize polypropylene surfaces in comparison with these intensively used industrial methods. Estimation of the influence of the nitrogen ion dose (from 1×10 15 to 1×10 16 ions/ cm 2 ) and the ion energy (from 60 to 100 eV) on incorporation is attempted in order to be able to use them in a controlled way. The ageing of these polymer surfaces in air and in water was studied by XPS for several months.

Analysis of the wear process of nitrogen implanted HSS stamping dies

Stamping dies for forming the cross-recessed heads of screws were implanted with various doses of 80keV nitrogen ions. The wear process during industrial production was studied by measurements of the evolution of wear land in the tool. An improvement by a factor of about 2.5 in the wear rate has been found. Tool chipping rate is reduced by a similar factor.

Theoretical and experimental investigations of defect evolution in silicon carbide during N + and Al + ion implantation taking into account internal stress fields

A theoretical model is developed which allows to describe the defect evolution in silicon carbide implanted with high doses of nitrogen and aluminium ions and subsequently annealed to form a solid solution. The diffusion of defects, the formation of complexes of defect clusters and the influence of the internal elastic stress fields produced by the implanted ions and the complexes formed are taken into account. Results from the simulations have been correlated with data obtained by Rutherford backscattering spectrometry/ion channelling (RBS/C).

Electron paramagnetic resonance study of ion implantation induced defects in amorphous hydrogenated carbon

Electron paramagnetic resonance (EPR) measurements have been made of defects in amorphous hydrogenated carbon (a-C:H) thin films. The films were grown on silicon substrates on the earthed electrode of an rf-powered plasma enhanced chemical vapour deposition reactor and were subsequently implanted with a range of doses of boron, carbon or nitrogen ions with energies from 20 keV to 32.5 keV. Two paramagnetic centres are observed, the carbon defect in the film with g = 2.0028(1) and a silicon defect in the substrate with g = 2.0058(6). The volume concentration of the carbon defect increases approximately linearly with dose, from approximately 3 x 10 17 cm -3 for unimplanted samples to 2.7 × 10 20 cm -3 at the highest implantation of 2 × 10 16 B + ions cm -2 . The increase in dose over this range also causes a narrowing of the EPR line (from 0.83 mT to 0.13 mT) and a significant decrease in the spin-lattice relaxation time (from 3 x 10 -5 s to 6 x 10 -8 s) which approaches the spin-spin relaxation time at the highest dose. The narrowing is attributed to motional averaging produced by either exchange or hopping. We also report the effects of annealing samples implanted with a range of boron doses. The prime novelty of this paper is that it is the first EPR study of defects produced by the implantation of a range of ions into polymer-like amorphous hydrogenated carbon.

Corrosion resistance of nitrogen-implanted Zircaloy-4 in high-temperature water

The influences of nitrogen implantation on the corrosion resistance of Zircaloy-4 were examined by immersion tests in high-temperature water at 350°C, and the results were discussed with structural and compositional variations of implanted layer that were measured by X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The nitrogen-implanted layer was composed either of ZrN and ZrO 2 layers or of nitrogen-implanted layer with ZrO 2 layer whether the implanted nitrogen ion dose is greater than the critical value of about 10 18 ions cm −2 necessary for the formation of ZrN layer or not. It was found that most of the nitrogen implanted into Zircaloy-4 was released into water when exposed to the high-temperature water, presumably by a decomposed reaction of ZrN by oxygen diffused from water, thereby producing ZrO 2 layer the thickness of which was very sensitive to both the substrate temperature and the nitrogen ion dose. The corrosion resistance of the nitrogen-implanted Zircaloy-4 was improved with increasing the ion dose, provided that the ion dose is less than the critical value for the formation of a continuous ZrN layer. The best corrosion resistance of Zircaloy-4 was obtained when implanted with a nitrogen ion dose of 5×10 17 ions cm −2 at a substrate temperature of 400°C due to an increased thickness of ZrO 2 layer.