Elastic Recoil Detection Analysis Method Research Articles

Quantitative hydrogen analysis through time of flight-elastic recoil detection analysis using medium energy ions

Quantitative hydrogen analysis is a useful tool in various fields, such as the energy, catalysts, and semiconductor fields, because the quality of materials or devices strongly depends on their hydrogen concentrations. To analyze the concentration of hydrogen quantitatively, the elastic recoil detection analysis (ERDA) method is widely used. In this report, the number fraction of hydrogen in silicon nitride was analyzed using a simple time-of-flight ERDA method over a depth range of 25 nm from the surface without the use of a stopping foil, an additional analyzer, or charged particle optics. The number fractions of the other elements (silicon and nitrogen) in the sample were also analyzed through backscattering measurements.

Analytical Possibilities of Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis Methods

This paper presents the results of an experimental study of three samples containing various elements in the near-surface layers. The depth profiles of all the elements of different atomic masses from hydrogen to silver were investigated by Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA). The experiments were performed by using the low-energy (about 2 MeV) 4He+ ion beams. The obtained results demonstrate the possibility of the RBS and ERDA methods in the investigation of depth profiles of any mass element with an atomic concentration of about 0.01 at.% and a depth resolution close to 10 nm.

Measurement of He and H depth profiles in tungsten using ERDA with medium heavy ion beams

Elastic recoil detection analysis method (ERDA) with medium heavy analyzing ion beam and its application for the simultaneous measurement of light elements in a very heavy substrate is presented. The availability of cross section data and the method of cross section calculation for recoiled particles are discussed. Different ion species for analyzing beam are discussed with respect to the cross-section data availability, sensitivity of the method, and the depth resolution. Calculations of depth resolution for each element and maximum depth of analysis for tungsten substrate are presented. The influence of the detector geometry and multiple scattering effects on the depth resolution is discussed. An example spectrum measured on tungsten implanted with He seeded D plasma is shown.

Dating study of two rock crystal carvings by surface microtopography and by ion beam analyses of hydrogen

Two artefacts made of rock crystal (quartz) from the collection of the Musee duquai Branly in Paris, France, a skull approximately half of the size of a real cranium and a smaller anthropomorphic head, purportedly attributed to pre-Columbian Mesoamerican cultures, were studied to assess their authenticity. The surface of the artefacts were examined by means of optical microscopy and scanning electron microscopy (SEM) and were analyzed nondestructively by ERDA (Elastic Recoil Detection Analysis), an ion beam analytical method that can measure hydrogen concentration profiles in depth. Optical and SEM imaging of tool marks indicates that the skull has been cut from a rock crystal block using machine lapidary techniques unavailable to pre-Columbian artisans, whereas the anthropomorphic head has more likely been carved and polished with manual techniques comparable to ancient ones. Hydrogen depth profiles in the first micron below the surface of the artefacts have been measured by ERDA with a 3-MeV He beam in a controlled helium atmosphere. Recently the progressive penetration of water at the surface of a quartz sample exposed to the natural environment has been proposed as a dating method (labeled quartz hydration dating or QHD) applicable to archaeological artefacts made of this material. The shallower penetration of H clearly indicates that the rock crystal skull was manufactured more recently than the reference quartz sample cut in 1740. As for the anthropomorphic head, the deep penetration profiles indicate an older artefact. Thus the converging micro-topographical examinations and hydrogen profiles of the samples surfaces indicate that the skull is probably not a pre-Columbian artefact but has been carved in the 18th or 19th century. The anthropomorphic head, on the other hand, could have been carved in the pre-Columbian period. In addition, the ERDA method carried out with an external beam presented here provides a new and simple approach for the nondestructive authentication of quartz-based archaeological artefacts by QHD.

Hard carbon coatings deposited on steel

We report results of steel substrates coated with hard amorphous carbon and with diamond films. In order to enhance the adherence to the substrate, steel substrates were pretreated by means of a silicon ion beam. Raman spectroscopy was used to analyze the structure of silicon interface while the elastic recoil detection analysis method was applied to determine their composition and thickness. The a-C adherence to the substrate and hardness were also tested. The diamond films were observed by SEM.

Studying permeation of hydrogen (H and D) through Palladium membrane dynamically with ERDA method

Permeation of H and D through palladium membrane was studied in real-time with Elastic Recoil Detection Analysis (ERDA). Concentration depth profile of hydrogen at the low pressure side of the membrane was followed by successive recording of ERDA spectra. Bulk concentration of hydrogen was high at low temperatures (below 380K and 420K for D and H, respectively) indicating that permeation is desorption limited. At higher temperatures concentration in the low pressure side of membrane diminished and hydrogen flux through the membrane increased as indicated by pressure rise in the vacuum chamber. Permeation of hydrogen therefore becomes diffusion limited.

Detection of N and B in doped diamond films by ERDA method and related electrochemical characteristics

Boron and nitrogen incorporation in diamond films grown by hot filament chemical vapor deposition (HFCVD) was investigated by elastic recoil detection analysis (ERDA). Boron concentration of only B-doped films ranges from 0.3% to 1.7%, which is related to the increase of B concentration into the gas phase from 0.2% to 1.5%. Two different sets of diamond films co-doped with B and N were investigated. The B incorporation into the films varied from 0.17% to 0.29% while the B concentration in the gas phase is increased from 0.2% to 2.0% and the N concentration in the films remains fixed. If the N 2 concentration of gas phase increases from 0.7% to 4.8% at a fixed B concentration, the B/C ratio of the films remains virtually unchanged (0.1 to 0.17%). Our results obtained from Scanning Electron Microscope (SEM), Raman Spectroscopy and 4 points resistivity measurements demonstrated that nitrogen incorporation modifies the characteristics of B-doped diamond films. In this article we also discuss the effect of film doping on the diamond electrode working potential window, which has been extended from 3.0 V to 3.5–4.0 V.

Measurements of Si ion stopping in amorphous silicon

The stopping of 28 Si ions in polycrystalline Si foils has been measured over the energy range 0.1–3.3 MeV per nucleon. For the low energy interval (0.1–0.5 MeV per nucleon), time of flight-energy elastic recoil detection analysis method was used, whilst for the high energy region (1.2–3.3 MeV per nucleon) the energy loss in the same foil was measured using a Si p–i–n diode with the 28 Si ions directly incident on the foil following acceleration. Below the stopping maximum the results are in good agreement with literature data based on Doppler shift measurements of short nuclear lifetimes but are about 20% smaller than the SRIM prediction. Above the stopping maximum the data are in agreement with SRIM within the limits of statistical uncertainty.

Effects of surface roughness on results in elastic recoil detection measurements

In order to study surface roughness effects on the elastic recoil detection analysis series of stainless steel samples were prepared to four different roughnesses by wet grinding and polishing. A multilayer film of B+C (20 nm thick)/Ti (220 nm)/B+C (20 nm) was electron beam evaporated on stainless steel samples and a flat silicon wafer. The time-of-flight elastic recoil detection analysis method utilizing a 53 MeV 127I 10+ beam was used to measure energy spectra of the recoiling sample elements. The topography of the samples was determined by atomic force microscopy and the film thickness by Rutherford backscattering spectrometry. A Monte Carlo simulation program which uses a measured surface structure and takes fully account of multiple scattering was written to simulate the elastic recoil measurements. Effects observed in the experimental energy spectra, like broadening of the peaks of deep lying layers, were reproduced in the simulations. Multiple scattering is the dominant factor behind the broadening for flat surfaces. It enhances strongly also the broadening due to the surface roughness.

Stoichiometry and impurity concentrations in II–VI compounds measured by elastic recoil detection analysis (ERDA)

Polycrystalline ZnSe will be used in a chemical vapour deposition process for thin-film solar-cell emitter layers. The precursor bulk material was characterised with respect to stoichiometry and impurity concentrations by the ERDA method, for which an experimental setup is installed at the Berlin Ion Beam Facility (ISL). The sample material was irradiated with high-energy Kr and Xe projectile ions of 120 and 250 MeV, respectively. The energy and time-of-flight (TOF) of the released sample atoms were detected. In contrast to the Rutherford backscattering technique the measurement of both parameters enables the separation of different masses not only in thin-films but also in bulk material. ERDA allows the simultaneous depth profiling of heavy and light elements including hydrogen. We found ZnSe bulk samples to exhibit an oxygen surface contamination with a Zn/O ratio of 1 : 2 and thickness of 27×10 15 at/cm 2. An accuracy in stoichiometry, i.e., Zn/Se ratio of better than 1% could be achieved and impurity concentrations could be detected down to the 100 ppm range. Detection limits of the ERDA technique and its capacity for concentration profiling in II–VI materials will be discussed.

Application of ERDA method to study hydrogen and helium in Ti, Zr and Nb membranes

Hydrogen and helium behavior in Ti, Zr and Nb membranes of several μm thickness was investigated by Elastic Recoil Detection Analysis (ERDA) using 6 MeV O and 12 MeV C beams in the transmission geometry. The concentration depth profiles of H and He during the 4He implantation were simultaneously measured in the membranes containing uniformly distributed H of about 0.1 at.%. During the 4He implantation into Ti, Zr and Nb membranes, an enrichment of the H concentration was observed at the depth corresponding to the range of the implanted 4He ions. In the Nb membrane, a reversible change of the H profile was observed on heating and cooling runs. The trapping energy of H in defects created by 10 keV 4He implantation in the Nb membrane was estimated to be 0.14 ± 0.03 eV from the change in H concentration on cooling after the 4He implantation at 500 K.

Hydrogen and deuterium profile in homoepitaxially grown CVD diamonds by ERDA method

Elastic recoil detection analysis (ERDA) was performed to determine H and D concentration profiles near the (100) surfaces of epitaxially grown diamond films. The other elements were analyzed by Rutherford backscattering spectrometry (RBS) at the same time. Microwave plasma chemical vapor deposition (CVD) was used for the growth. After the growth, the specimens were treated with H 2, H 2 O 2 , D 2 or D 2 O 2 plasma. The areal densities of H determined by ERDA ranged from 3 to 4 × 10 15 atoms/cm 2 near the surface of all specimens. Deuterium densities of the samples treated with D 2 or D 2 O 2 plasma ranged from 1 to 2 × 10 15 atoms/cm 2. These areal densities were two to three times larger than that of C atoms on the ideal (100) surface of diamond (∼ 1.6 × 10 15 atoms/cm 2).

Coadsorption of hydrogen and deuterium on Si(100) surfaces studied by elastic recoil detection analysis

We have carried out coadsorption experiments of hydrogen (H) and deuterium (D) to investigate the dynamic behavior of hydrogen adsorption on Si(100) surfaces. During the experiments, changes in H and D on the surface are quantitatively measured by an elastic recoil detection analysis method using a 6 MeV F 3+ ion beam. In the process of H adsorption onto D-adsorbed surfaces at both room temperature and 350°C, we found that the H concentration shows a gradual increase accompanied by a gradual decrease in the D concentration. A similar result is obtained for D adsorption onto H-adsorbed surfaces at the same temperatures. As a dynamic behavior, substitution between the adsorbed hydrogen and the atomic hydrogen impinging upon the surface is strongly suggested.

Hydrogen profiles of thin PVD silicon nitride films using elastic recoil detection analysis

Thin silicon nitride films (e.g. D = 100 nm) produced by the ion beam sputtering technique show different depth profiles of hydrogen concentration depending on process parameters. The hydrogen profiles of these thin films can be varied within certain limits by annealing. Films prepared on a silicon substrate have been analysed with respect to the hydrogen content by the elastic recoil detection analysis method (ERDA) using a 10 MeV 20Ne beam impinging on the target at an incident angle of φ = 10° relative to the ion beam axis. Comparison of the results of the ERDA with the results from analyses using the nuclear reaction 1H(15N, αγ)12C shows good agreement. The experimental results illustrate the advantage of the PVD sputtering deposition technique in controlling the hydrogen concentration of thin silicon nitride films.

Annealing-temperature influence on the dispersive diffusion of hydrogen in undoped a-Si:H.

We have measured by the method of elastic-recoil detection analysis the variation of the dispersion parameter \ensuremath{\alpha} of hydrogen diffusion in undoped a-Si:H as a function of the annealing temperature ${\mathit{T}}_{\mathit{a}}$ between 350 and 470 \ifmmode^\circ\else\textdegree\fi{}C. We found that \ensuremath{\alpha} increases with ${\mathit{T}}_{\mathit{a}}$. We suggest a mechanism which can explain this new result, as well as the variation of \ensuremath{\alpha} with the film-deposition temperature reported earlier.

Dispersive diffusion of hydrogen in a-Si:H: Influence of the film deposition temperature.

We have measured by the method of elastic-recoil detection analysis the dispersion parameter \ensuremath{\alpha} of hydrogen diffusion in undoped a-Si:H. We find that a lowering of the deposition temperature of the films increases the value of \ensuremath{\alpha}. This variation can also be clearly correlated with the increase of the initial concentration of weakly bound hydrogen, which is expected to reflect the disorder of the microstructure. These results will certainly contribute to the elucidation of the dispersive character of the diffusion of hydrogen in the different types of amorphous silicon.