Heavy Ion Elastic Recoil Detection Analysis Research Articles

Energy loss straggling data of 63Cu, 28Si, 27Al, 24Mg, 19F and16O heavy ions crossing thin polymeric foils at low energy

Throughout this work we present and analyse the inter-comparison result that we carried out between the energy loss straggling of 63Cu, 28Si, 27Al, 24Mg, 19F and16O partially stripped heavy ions crossing thin polymeric foils such as: Mylar, Polypropylene, Plexiglas and PVC, over a continuous range of energies 0.045–0.62 MeV/n, obtained experimentally and those calculated by the different theoretical formulations defining the energy loss straggling namely; straggling of Bohr, Bethe-Livingston, Lindhard-Scharff and the empirical formula developed by Yang et al. The experimental straggling data obtained in the framework with a precision of ±20% and nonexistent in the literature so far, have been generated by using Heavy Ion Elastic Recoil Detection Analysis (HIERDA) technique coupled with Time of Flight (ToF) spectrometer. In view of significant deviations obtained between experimental straggling data and those calculated theoretically, we can say that Bohr’s classical theory and other theories derived from Bohr’s classical theory (Lindhard-Scharff, Bethe-Livingston or Yang) are insufficient to describe correctly our obtained experimental straggling data over the investigated energy range.

In-situ measurements of magmatic volatile elements, F, S, and Cl, by electron microprobe, secondary ion mass spectrometry, and heavy ion elastic recoil detection analysis

AbstractElectron probe and ion probe are the two most used instruments for in situ analysis of halogens in geological materials. The comparison of these two methods on widely distributed glass standards (example: MPI-DING glasses, Jochum et al., G-cubed, 2006) provides a basis for establishing laboratory method, independent geochemical data sets for these elements. We report analyses of F, S, and Cl concentrations in three geological glass samples (EPMA) and 10 referenced standards (EPMA and SIMS). Furthermore, F and Cl absolute abundances have been determined independently for three of the standards (KL2-G, ATHO-G, and KE12), via heavy ion elastic recoil detection analysis (HIERDA), to certify the accuracy of the cross-calibration EPMA-SIMS. The detection limits for EPMA are a 150 μg·g-1 for F, 20 μg·g-1 for S and Cl, and for SIMS < 48 μg·g-1 for F, < 3 μg·g-1 for S, and <19 μg·g-1 for Cl. On SiO2-rich glass-standards, F and Cl measurements by HIERDA highlight a weak matrix effect during SIMS analysis of F and Cl. With the HIERDA independently measured value, we therefore propose an alternative calibration function to empirically correct this matrix effect on the SIMS measurements of F, S, and Cl.

Energy loss and stopping force of heavy ions Cu, Si, Al and F through thin Nickel (Ni) foil at low MeV energies

The slowing down of Cu, Si, Al and F heavy ions over the 0.09–0.51 MeV/nucleon energy range in thin Nickel (Ni) foil has been investigated by using the Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with a time of flight (ToF) spectrometer. This experimental setup generated a significant amount of energy loss data, which allowed the determination of stopping force of 63Cu7+ heavy ions in Nickel at low projectile energies. The obtained stopping force results were compared with semi-empirical calculations by Ziegler’s Stopping and Range of Ions in Matter (SRIM) code, and ab initio calculations by Grande and Schiewietz’s Convolution approximation for swift Particles (CasP) code. The aim of such comparison was to assess the reliability and accuracy of the existing energy loss formulations, in the light of the present experimental results. Good agreement was found between the experimental stopping force data for the reported ions velocities and SRIM predictions. For CasP, the agreement is fairly good from ∼0.15 MeV/n onwards.

Crystal damage analysis of implanted AlxGa1-xN (0 ≤ x ≤ 1) by ion beam techniques

In this work ion implantation effects in AlxGa1−xN alloys were investigated by ion beam analysis, namely, Rutherford backscattering spectrometry/channelling (RBS/C) and heavy ion elastic recoil detection analysis (HI-ERDA) in order to assess the contribution of the AlN content on the radiation resistance and elemental distribution. AlxGa1−xN films (0 ≤ x ≤ 1) were implanted at room temperature (RT) with different ions (200 keV argon (Ar), 300 keV xenon (Xe) and 300 keV europium (Eu)). Unexpectedly, RBS/C reveals that the radiation damage at high fluences is increased for high AlN molar fractions despite of lower damage production cross sections in AlN as compared to GaN. The comparison of different ion masses allowed concluding that this effect is independent of the cascade density. Complementary HI-ERDA of Ar implanted AlxGa1−xN alloys revealed a nitrogen deficiency in the implanted layer for high AlN content alloys which may be the reason for their unexpected damage formation behaviour.

Slowing down of 2–11 MeV 12C, 16O, 28Si and 63Cu heavy ions through Si3N4 thin foil by using Time-of-Flight spectrometry

The stopping force and the energy-loss straggling of 63Cu, 28Si, 16O and 12C partially stripped heavy ions crossing silicon nitride foil has been determined over a continuous range of energies 2–11MeV, by using a method based on the Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique using a Time of Flight (ToF) spectrometer. The obtained energy loss straggling values corrected for non-statistical straggling and the thickness variation using the Besenbacher’s method have been analyzed and compared with the corresponding computed values. For computed electronic straggling we have used alternatively the widely used formulations such as, the universal Bohr straggling deduced from the Bohr stopping model, and the Lindhard–Scharff formula including the Bunching effect given by Hvelplund–Firsov formula according to the Besenbacher approach. The aim of such comparison is to check the reliability and accuracy of the existing energy loss straggling formulations, in the light of the present experimental results. The experimental results of energy loss straggling of all ions are found to be greater than those predicted by the Bohr stopping model or Lindhard–Scharff prediction model. The introduction of the bunching effect improves the comparison and gives an estimation of other effects such as charge exchange.

Energy loss measurements of 63Cu, 28Si and 27Al heavy ions crossing thin Polyvinylchloride (PVC) foil

Experimental stopping data of, 63Cu, 28Si and 27Al heavy ions in thin Polyvinylchloride (H3C2Cl1) foil have been obtained over the 0.045–0.50MeV/nucleon energy range. The measured energy losses were carried out by Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer. A continuous stopping power data obtained in this work are well fitted by our proposed semi-empirical formula and the results are compared to those calculated by LSS formula or generated by SRIM-2013 and MSTAR predictions. Calculations using our formula agree well with the obtained experimental stopping powers, while the LSS formula underestimates the experimental data in the whole investigated energy range. In this work a simple expression for electronic stopping power of heavy ions at low energy in solid targets is introduced. This formula is based on the Firsov and Lindhard–Sharff stopping power models with a small modification made to the original expression, by incorporating the effective charge of moving ions concept and with exponential fit function.

Implementation of heavy-ion elastic recoil detection analysis at JANNUS-Saclay for quantitative helium depth profiling

Quantitative depth profiling measurements of implanted light elements is an important issue for electronics and nuclear applications. Conventional elastic recoil detection analysis (ERDA) has been improved by using heavy ions as incident particles for quantitatively profiling helium in materials.A new system has been implemented on the triple beam irradiation platform JANNUS at Saclay devoted to carry out HI-ERDA measurements. This device is dedicated to helium depth profiling using a 15MeV 16O5+ incident ion beam. Capabilities of the technique (quantitative analysis, resolution and limit of detection) were tested on samples of known composition.For the first time, 4He depth profiles in pure α-iron, as-implanted and annealed, are obtained. HI-ERDA measurements have shown that helium release in pure α-iron can be described by a succession of two steps, the first having a slow kinetics below 700°C and the second with a fast kinetics above 700°C.

Ion beam effects of 26.0 MeV Cu7+ ions in thin metallic and insulating films during Heavy Ion ERDA measurements

We report on an investigation carried out to determine effects of the probing beam on the structure of typical metallic and insulating thin films during Elastic Recoil Detection Analysis (ERDA) using a heavy ion beam. Metallic niobium nitride (NbN) and insulating calcium fluoride (CaF2) thin films (used as test samples) were irradiated by 26.0MeV 63Cu7+ ions to fluences of 1.70×1014ions/cm2 and 2.70×1014ions/cm2, respectively. The effects of irradiation on the structural properties of the films were studied using Rutherford Backscattering Spectrometry (RBS), X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). RBS results showed a significant (18%) reduction in the thickness of the CaF2 film due to electronic sputtering compared to only 1% reduction in the NbN film. XRD results showed no significant peak shifts in both films, but rather formation of unidentified peaks in the insulating film. AFM results indicated a substantial decrease in the average surface roughness of the insulating film and only a nominal increase in that of the metallic film. Results of electronic sputtering yield measurements carried out by ERDA are explained in terms of both the Coulomb explosion and the inelastic thermal spike models.

Energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil over a range of energies 0.1–0.6MeV/u by time-of-flight spectrometry

The energy-loss straggling of 28 Si, 27 Al, 24 Mg, 19 F, 16 O and 12 C partially stripped heavy ions has been determined in Formvar polymeric thin foil over a continuous range of energies 0.1–0.6 MeV/u, by using a powerful method based on the combination of Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique and Time of Flight (ToF) spectrometer. The obtained energy loss straggling values have been analyzed and compared with the corresponding computed values adopting some widely used energy loss straggling formulations such as, Bohr, Bethe–Livingston and Yang formulas. The aim of such a comparison is to check the reliability and accuracy of the existing energy loss straggling formulations. The experimental results of energy loss straggling of all ions are found to be significantly greater than those predicted by the theories. These differences can be attributed to the charge exchange straggling. This effect has to be taken into account in order to explain the obtained results. • Measurement of energy loss straggling data of 28 Si, 27 Al, 24 Mg, 19 F, 16 O, and 12 C heavy ions in thin polymeric Formvar foil. • The heavy ion elastic recoil detection analysis (HIERDA) technique coupled with time of flight (ToF) spectrometer was used. • The aim of such a study is to check the reliability and accuracy of the existing energy loss straggling formulations.

Iodine assisted retainment of implanted silver in 6H-SiC at high temperatures

The effect of high temperature thermal annealing on the retainment and diffusion behaviour of iodine (I) and silver (Ag) both individually and co-implanted into 6H-SiC has been investigated using RBS, RBS-C and heavy ion ERDA (Elastic Recoil Detection Analysis). Iodine and silver ions at 360keV were both individually and co-implanted into 6H-SiC at room temperature to fluences of the order of 1×1016cm−2. RBS analyses of the as-implanted samples indicated that implantation of Ag and of I and co-implantation of 131I and 109Ag at room temperature resulted in complete amorphization of 6H-SiC from the surface to a depth of about 290nm for the co-implanted samples. Annealing at 1500°C for 30h (also with samples annealed at 1700°C for 5h) caused diffusion accompanied by some loss of both species at the surface with some iodine remaining in the iodine implanted samples. In the Ag implanted samples, the RBS spectra showed that all the Ag disappeared. SEM images showed different recrystallization behaviour for all three sets of samples, with larger faceted crystals appearing in the SiC samples containing iodine. Heavy Ion ERDA analyses showed that both 109Ag and 131I remained in the co-implanted SiC samples after annealing at 1500°C for 30h. Therefore, iodine assisted in the retainment of silver in SiC even at high temperature.

An overview of the comprehensive First Mirror Test in JET with ITER-like wall

The First Mirror Test in Joint European Torus (JET) with the International Thermonuclear Experimental Reactor-like wall was performed with polycrystalline molybdenum mirrors. Two major types of experiments were done. Using a reciprocating probe system in the main chamber, a short-term exposure was made during a 0.3 h plasma operation in 71 discharges. The impact on reflectivity was negligible. In a long-term experiment lasting 19 h with 13 h of X-point plasma, 20 Mo mirrors were exposed, including four coated with a 1 μm-thick Rh layer. Optical performance of all mirrors exposed in the divertor was degraded by up to 80% because of beryllium, carbon and tungsten co-deposits on surfaces. Total reflectivity of most Mo mirrors facing plasma in the main chamber was only slightly affected in the spectral range 400–1600 nm, while the Rh-coated mirror lost its high original reflectivity by 30%, thus decreasing to the level typical of molybdenum surfaces. Specular reflectivity was decreased most strongly in the 250–400 nm UV range. Surface measurements with x-ray photoelectron spectroscopy and depth profiling with secondary ion mass spectrometry and heavy-ion elastic recoil detection analysis (ERDA) revealed that the very surface region on both types of mirrors had been modified by neutrals, resulting eventually in the composition change: Be, C, D at the level below 1 × 1016 cm−2 mixed with traces of Ni, Fe in the layer 10–30 nm thick. On several exposed mirrors, the original matrix material (Mo) remained as the major constituent of the modified layer. The data obtained in two major phases of the JET operation with carbon and full metal walls are compared. The implications of these results for first mirrors and their maintenance in a reactor-class device are discussed.

Heavy ion elastic recoil detection analysis of AlxOy/Pt/AlxOy multilayer selective solar absorber

An AlxOy/Pt/AlxOy multilayer solar absorber for use in solar-thermal applications has been deposited onto copper substrate by electron beam (e-beam) vacuum evaporation at room temperature. Different samples were annealed at different temperatures in air and characterized by spectrophotometry, emissometry, heavy ion elastic recoil detection analysis (HI-ERDA), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The AlxOy/Pt/AlxOy multilayer solar absorbers heated up to 500°C were found to exhibit good spectral selectivity (α/ɛ) of 0.951/0.08. However, beyond 500°C the spectral selectivity decreased to 0.846/0.11, possibly due to thermally activated atomic interdiffusion profiles. HI-ERDA has been used to study depth-dependent atomic concentration profiles. These measurements revealed outward diffusion of the copper substrate towards the surface and therefore, the decrease in the constituents of the coating. The decrease in the intensity of Pt grains and formation of CuO and Cu2O phases at 700°C were confirmed by XRD and EDS.

Compositional analysis and depth profiling of thin film CrO2 by heavy ion ERDA and standard RBS: a comparison

Chromium dioxide (CrO 2 ) thin film has generated considerable interest in applied research due to the wide variety of its technological applications. It has been extensively investigated in recent years, attracting the attention of researchers working on spintronic heterostructures and in the magnetic recording industry. However, its synthesis is usually a difficult task due to its metastable nature and various synthesis techniques are being investigated. In this work a polycrystalline thin film of CrO 2 was prepared by electron beam vaporization of Cr 2 O 3 onto a Si substrate. The polycrystalline structure was confirmed through XRD analysis. The stoichiometry and elemental depth distribution of the deposited film were measured by ion beam nuclear analytical techniques heavy ion elastic recoil detection analysis (ERDA) and Rutherford backscattering spectrometry (RBS), which both have relative advantage over non-nuclear spectrometries in that they can readily provide quantitative information about the concentration and distribution of different atomic species in a layer. Moreover, the analysis carried out highlights the importance of complementary usage of the two techniques to obtain a more complete description of elemental content and depth distribution in thin films. Heavy ion elastic recoil detection analysis (ERDA) and Rutherford backscattering spectrometry (RBS) both have relative advantage over non-nuclear spectrometries in that they can readily provide quantitative information about the concentration and distribution of different atomic species in a layer. ► Thin films of CrO 2 have been grown by e-beam evaporation of Cr 2 O 3 target in vacuum. ► The composition was determined by heavy ion—ERDA and RBS. ► HI-ERDA and RBS provided information on the light and heavy elements, respectively.

Heavy ion energy loss straggling data from Time of Flight stopping force measurements

The accuracy of heavy ion beam analytical techniques such as Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) depends on, among other factors, the accuracy of basic ion beam data such as stopping force and energy loss straggling, used as input in ion beam analysis programs. The adaptation of the Time of Flight (ToF) ERDA technique for stopping force measurements in free standing target foils brings with it the possibility of extracting energy loss straggling information from the ToF derived energy spectra. In essence several straggling values can be obtained over a continuous energy range from a single measurement. A presentation is made here of an exploration of that possibility using the passage of 12C, 16O, 27Al and 84Kr ions in the oxide ceramic ZrO 2 as examples. The experimental straggling values, obtained over the 0.1–0.6 MeV/u energy range, are normalised to Bohr straggling and compared with Yang’s empirical formulation, which is widely used in ion beam analysis programs.

Enhancement in the photocatalytic nature of nitrogen-doped PVD-grown titanium dioxide thin films

Nitrogen-doped titanium dioxide semiconductor photocatalytic thin films have been deposited by unbalanced reactive magnetron physical vapor deposition on glass substrates for self-cleaning applications. In order to increase the photocatalytic efficiency of the titania coatings, it is important to enhance the catalysts absorption of light from the solar spectra. Bearing this fact in mind, a reduction in the titania semiconductor band-gap has been attempted by using nitrogen doping from a coreactive gas mixture of N2:O2 during the titanium sputtering process. Rutherford backscattering spectroscopy was used in order to assess the composition of the titania thin films, whereas heavy-ion elastic recoil detection analysis granted the evaluation of the doping level of nitrogen. X-ray photoelectron spectroscopy provided valuable information about the cation-anion binding within the semiconductor lattice. The as-deposited thin films were mostly amorphous, however, after a thermal annealing in vacuum at 500 °C the crystalline polymorph anatase and rutile phases have been developed, yielding an enhancement in the crystallinity. Spectroscopic ellipsometry experiments enabled the determination the refractive index of the thin films as a function of the wavelength, while from the optical transmittance it was possible to estimate the semiconductor indirect band-gap of these coatings, which has been proven to decrease as the N-doping increases. The photocatalytic performance of the titania films has been characterized by the degradation rate of an organic reactive dye under UV/visible irradiation. It has been found that for a certain critical limit of 1.19 at. % of nitrogen doping in the titania anatase crystalline lattice enhances the photocatalytic behavior of the thin films and it is in accordance with the observed semiconductor band-gap narrowing to 3.18 eV. By doping the titania lattice with nitrogen, the photocatalytic activity is enhanced under both UV and visible light.

Considerations about multiple and plural scattering in heavy-ion low-energy ERDA

Low-energy heavy-ion Elastic Recoil Detection Analysis (ERDA) is becoming a mature technique for high-resolution characterization of thin films, i.e. below 50nm thickness. In combination with a small tandem accelerator (∼2MV terminal voltage) and beam energies below 20MeV, it is suitable for routine analysis of key materials in semiconductor technology.At low-energies, however, small angle multiple scattering and large angle plural scattering of ions play a significant role, starting from the first nanometers. Multiple and plural scattering dominate the depth resolution deterioration with increasing depth and, when glancing angles are used, introduce long tails in the elemental energy profiles. Moreover, multiple and plural scattering may affect the elemental relative and absolute quantification. A complete characterization of ultra-thin films thus requires a detailed analysis with accurate simulation of the energy spectra.In this paper we investigate the mechanism of multiple and plural scattering for different combinations of beam/recoil atoms, energies and geometries. Simulations run with the Monte Carlo code MCERD support and generalize the experimental data. The calculations show the relative contributions of beam and recoil ions and highlight the role of ion angular distribution to the formation of tails in the energy profiles.

Structural and optical properties of nitrogen doped ZnO films

Zinc oxide is getting an enormous attention due to its potential applications in a variety of fields such as optoelectronics, spintronics and sensors. The renewed interest in this wide band gap oxide semiconductor relies on its direct high energy gap ( E g ∼ 3.437 eV at low temperatures) and large exciton binding energy. However to reach the stage of device production the difficulty to produce in a reproducible way p-type doping must be overcome. In this study we discuss the structural and optical properties of ZnO films doped with nitrogen, a potential p-type dopant. The films were deposited by magnetron sputtering using different conditions and substrates. The composition and structural properties of the films were studied combining X-ray diffraction (XRD), Rutherford backscattering (RBS), and heavy ion elastic recoil detection analysis (HI-ERDA). The results show an improvement of the quality of the films deposited on sapphire with increasing radio-frequency (RF) power with a preferentially growth along the c-axis. The ERDA analysis reveals the presence of H in the films and a homogeneous composition over the entire thickness. The photoluminescence of annealed samples evidences an improvement on the optical quality as identified by the well structured near band edge recombination.

Physical properties of high pressure reactively sputtered hafnium oxide

Hafnium oxide films were deposited on silicon by High Pressure Reactive Sputtering (HPRS) at pressures between 0.8 and 1.6 mbar. Growth, composition and morphology were investigated using Transmission Electron Microscopy (TEM), Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA), Fourier Transform Infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD). The growth rate was found to decrease exponentially with deposition pressure. The films showed a monoclinic polycrystalline structure, with higher grain size for intermediate pressures. All the films were slightly oxygen rich with respect to stoichiometric HfO 2, which is attributed to the oxygen plasma. Additionally, it was observed the formation of an interfacial silicon oxide layer, with a minimum thickness for deposition pressures around 1.2 mbar. These results are explained by the oxidation action of the oxygen plasma and the diffusion of oxygen through the grain boundaries of the HfO 2 film.

The use of HI-ERDA/RBS and NRA/RBS to depth profile N in GaAs1−xNx thin films

N profiles of several GaAs1−xNx epitaxial layers with different N mole fractions in the range 0<x<0.14 were obtained by using (1) heavy-ion elastic recoil detection analysis (HI-ERDA) along with Rutherford backscattering spectrometry (RBS) using a 35MeV Si6+ beam, and (2) nuclear reaction analysis (NRA) with the 14N(α,p)17O reaction, also with RBS, using a 3.7MeV 4He+ beam. The results from the two techniques are compared and the advantages, disadvantages and capabilities are discussed.

Optical properties and structure of HfO2 thin films grown by high pressure reactive sputtering

Thin films of hafnium oxide (HfO2) have been grown by high pressure reactive sputtering on transparent quartz substrates (UV-grade silica) and silicon wafers. Deposition conditions were adjusted to obtain polycrystalline as well as amorphous films. Optical properties of the films deposited on the silica substrates were investigated by transmittance and reflectance spectroscopy in the ultraviolet, visible and near infrared range. A numerical analysis method that takes into account the different surface roughness of the polycrystalline and amorphous films was applied to calculate the optical constants (refractive index and absorption coefficient). Amorphous films were found to have a higher refractive index and a lower transparency than polycrystalline films. This is attributed to a higher density of the amorphous samples, which was confirmed by atomic density measurements performed by heavy-ion elastic recoil detection analysis. The absorption coefficient gave an excellent fit to the Tauc law (indirect gap), which allowed a band gap value of 5.54 eV to be obtained. The structure of the films (amorphous or polycrystalline) was found to have no significant influence on the nature of the band gap. The Tauc plots also give information about the structure of the films, because the slope of the plot (the Tauc parameter) is related to the degree of order in the bond network. The amorphous samples had a larger value of the Tauc parameter, i.e. more order than the polycrystalline samples. This is indicative of a uniform bond network with percolation of the bond chains, in contrast to the randomly oriented polycrystalline grains separated by grain boundaries.