Elastic Recoil Detection Method Research Articles

Measurement of theH2(p,γ)He3Sfactor at 265–1094 keV

Recent astronomical data have provided the primordial deuterium abundance with percent precision. As a result, Big Bang nucleosynthesis may provide a constraint on the universal baryon to photon ratio that is as precise as, but independent from, analyses of the cosmic microwave background. However, such a constraint requires that the nuclear reaction rates governing the production and destruction of primordial deuterium are sufficiently well known. Here, a new measurement of the $^2$H($p,\gamma$)$^3$He cross section is reported. This nuclear reaction dominates the error on the predicted Big Bang deuterium abundance. A proton beam of 400-1650keV beam energy was incident on solid titanium deuteride targets, and the emitted $\gamma$-rays were detected in two high-purity germanium detectors at angles of 55$^\circ$ and 90$^\circ$, respectively. The deuterium content of the targets has been obtained in situ by the $^2$H($^3$He,$p$)$^4$He reaction and offline using the Elastic Recoil Detection method. The astrophysical S-factor has been determined at center of mass energies between 265 and 1094 keV, addressing the uppermost part of the relevant energy range for Big Bang nucleosynthesis and complementary to ongoing work at lower energies. The new data support a higher S-factor at Big Bang temperatures than previously assumed, reducing the predicted deuterium abundance.

Study of Mos Structures Using Nuclear Analytical Methods

The atomic concentrations and depth distribution of elements in MOS (metal oxide semiconductor) structures have been investigated using two nuclear analytical methods: Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection (ERD). The elements with atomic masses in range from hydrogen up to copper were identified. Their depth profiles show that a MOS structure consists from metal (Al) layer, silicon oxide layer and a silicon substrate. The heavy elements Cu, Ti were found at near-surface area of one sample with low concentrations. The transitional area between the silicon substrate and the oxide layer as well as between the metal and oxide layers was noticed. The obtained results provide valuable information about MOS structures and concurrently demonstrate possibilities of both RBS and ERD methods in material analysis.

ERDA 40 years ago: The development of ERDA

In this paper it will be explained how the elastic recoil detection method was developed. This development came from the close collaboration of two groups of scientists coming from different horizons: one group was composed of surface scientists and the other of nuclear physicists. This led to the development of ERDA and to the solution of a difficult technical problem: the corrosion of internal walls of nuclear reactors. The original documents will be used to describe the different steps of this development. It will also be shown that the power of ERDA was rapidly recognized by the scientific community. In addition, some of the problems that were met during this development are discussed and some conclusions are drawn from this experience.

Hydrogen and deuterium distribution in tungsten foils irradiated with high-temperature deuterium plasma in H2O- or D2O-filled hermetic chambers

Processes of deuterium and hydrogen accumulation and redistribution are studied via the elastic recoil detection method with the help of a Plasma Focus (PF-4) setup. These processes proceed when high-temperature pulsed deuterium plasma acts on two external tungsten foils used as the main elements of hermetic chambers filled with distilled or heavy water and one internal tungsten foil inserted into an aqueous medium. It is established that, under the action of pulsed deuterium plasma on the heavy water-filled chamber, implanted deuterium atoms and those existing in the heavy water, as well as hydrogen contained in the tungsten foils, are redistributed over the entire thicknesses of the three foils. When the distilled water-filled chamber is irradiated with pulsed deuterium plasma, implanted hydrogen is observed across the whole thickness of the external tungsten foils with a depth distribution maximum. Hydrogen and deuterium reach their maxima on the foil surface immersed in liquid. The revealed phenomenon can be explained by the fact that chemical bonds in the heavy and distilled water are broken and, afterward, free hydrogen and deuterium atoms are transferred to tungsten foils under the action of intense shock waves excited in the chamber.

Effect of the hydrogen concentration on the growth mechanism of sputtered hydrogenated silicon thin films

The method of elastic recoil detection (ERD) has been utilized to analyze the actual hydrogen concentration in hydrogenated silicon thin films and has been demonstrated to provide more stable and accurate analysis for quantification of the hydrogen concentration than does Fourier Transform Infrared Spectroscopy. In order to realize the quality of thin films, spectroscopic ellipsometry and the applied effective medium approximation (EMA) theory of the Maxwell-Garnett and Bruggeman models are applied to deducing the effective refractive index of the films. The relative void fractions corresponding to amorphous silicon films with lowest hydrogen flow could be obtained based on the EMA theory. Therefore, this study found an important linear relationship between the hydrogen concentration and structural relaxation as a consequence of the void fraction induced by the hydrogen flow.

Nuclear and Optical Analyses of MOS Devices

The characteristic dome-like shape distribution of electric parameters (with the biggest values in the middle and the lowest values in the corners of the gate) has been observed in our investigations. Taking the results of the papers into account, the following hypothesis was drawn: the shape distribution of electrical parameters has been caused by the irregular shape of stress distribution under the metal gate. To prove or deny the assumed hypothesis, a lot of investigations on stress and strain in MOS structures are being performed. The study of the atomic composition of electronic components constitutes the starting point of their characterization. Therefore, in this paper, we present experimental results of hydrogen, oxygen, aluminum, silicon, and copper concentrations in MOS structures carried out by the Rutherford backscattering spectrometry and elastic recoil detection methods. These techniques allow inter alia determination of silicon and oxygen content as a function of the position x on a wafer. On the basis of depth pro le elastic recoil detection measurements performed on Al and AlSiCu gates, a much larger hydrogen content in the surface layer for MOS structure with Al gate was con rmed. Copper atoms were detected only in the AlSiCu gate.

Characterization of Nanocrystalline Diamond/Amorphous Composite Carbon Films Prepared by PECVD Technology

Nanocrystalline diamond/amorphous composite carbon films were deposited by plasma enhanced chemical vapour deposition method. The concentrations of species in the films were determined by RBS (Rutherford backscattering spectrometry) and ERD (elastic recoil detection) methods. The RBS results showed the main concentrations of C in the films. The concentration of hydrogen was approximately 20 at. %. Chemical compositions were analyzed by FTIR spectroscopy. IR results showed the presence of C-H specific bonds. Film was used for photocathode application. The original quantum efficiency of prepared photocathode at energy of FH 15,6 mJ was 1,43x10 -6 %.

ALD Grown Aluminum Oxide Submonolayers in Dye-Sensitized Solar Cells: The Effect on Interfacial Electron Transfer and Performance

Effects of atomic layer deposited (ALD) aluminum oxide barriers on electron injection, recombination reactions, and efficiency of dye-sensitized solar cells were studied. The amorphous AlOx submonolayers prepared on nanocrystalline 2 μm thick TiO2 anatase film were characterized by high-resolution transmission electron microscopy. Time-of-flight elastic recoil detection method was employed to study the growth of similar AlOx layers on planar anatase films. Density functional theory calculations of the first ALD cycle over a (101) anatase surface revealed atomic scale roughness of the deposited layer owing to unequal adsorption sites and lateral repulsions between adsorbed precursor molecules. Calculations also indicate that the holes in the first AlOx layer allow triiodide but not the ruthenium bipyridyl sensitizer to reach the TiO2 surface. After the first deposition cycle the dye binds to AlOx and is in average about 0.2 nm farther from the TiO2 surface than when binding to the bare TiO2 surface. Increa...

Deposition of hard thin films from HMDSO in atmospheric pressure dielectric barrier discharge

An atmospheric pressure dielectric barrier discharge burning in nitrogen with a small admixture of hexamethyldisiloxane (HMDSO) was used for the deposition of thin organosilicon films. The thin films were deposited on glass, silicon and polycarbonate substrates, and the substrate temperature during the deposition process was increased up to values within the range 25–150 °C in order to obtain hard SiOx-like thin films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterized by the Rutherford backscattering and elastic recoil detection methods, x-ray photoelectron spectroscopy, infrared spectroscopy measurements, ellipsometry and the depth sensing indentation technique. It was found that the films' properties depend significantly on the substrate temperature at deposition. An increase in substrate temperature from 25 to 150 °C led to an increase in film hardness from 0.4 to 7 GPa and the film chemical composition changed from CHxSiyOz to SiOxHy. The films were transparent in the visible range.

Postannealing effect on properties of hydrogenated amorphous Si(Mn) magnetic semiconductors

Postannealing effect was studied on films of hydrogenated amorphous silicon with Mn addition grown by magnetron cosputtering. Structural, magnetic, and electrical properties were investigated. We did not detect any second phases or clusters after annealing. Annealing enhances saturation magnetization, electrical conductivity, and carrier concentration by about 250%, 350%, and two orders of magnitude, respectively. Anomalous Hall effect was observed at 100 K, indicating ferromagnetism mediated by charge carriers. Moreover, the hydrogen concentration was determined by elastic recoil detection methods. The results revealed that there is no hydrogen effusion during annealing. The reason of property enhancement by annealing arises from the thermal energy to promote hydrogen diffusion; hence, a more homogeneous distribution and lessens defect density.

The mechanical properties of the SiOC(H) composite thin films with a low dielectric constant

SiOC(H) composite films with a low dielectric constant are deposited by an inductively coupled plasma chemical vapor deposition system with bis-trimethylsilymethane (BTMSM: H9C3SiCH2SiC3H9) precursor and oxygen gases. Mechanical properties such as hardness, elastic modulus and the atomic density of the film, which are very important for the application of thin films, are investigated by nano-indentation and elastic recoil detection methods. Fourier transform infrared spectroscopy is used to determine SiO and SiCH3 bonding configurations in the films. The formation of the SiOC ring-link mode by attaching CH3 groups to the SiOSi ring-link mode is responsible for the formation of nano-size voids in the film, and porosity depends on the carbon concentration in the film. The hardness and elastic modulus of the annealed SiOC(H) films are measured as 0.38∼0.43 and 4.0∼7.4 (GPa), respectively. A density of as-deposited film is reduced from 1.83 to 1.16 gcm−3 by annealing. The lowest dielectric constant of the annealed film is 2.1, in which the porosity and carbon concentration are 62 and 11%, respectively. The porosity increase within SiOC(H) film tends to decrease the hardness and elastic modulus of film.

Re-emission of hydrogen implanted into graphite by helium ion bombardment

Helium ion-induced re-emission of hydrogen implanted in graphite with 5 keV H 2 + ion beam at room temperature has been investigated in the energy range from 60 to 200 keV, by means of a high energy elastic recoil detection method with 16 MeV O 5+ ion beam. The hydrogen concentrations in graphite rapidly decrease with increasing the He + ion fluence and reach a constant value of H/C≅0.2. The re-emission rates of hydrogen from graphite increase with decreasing incident energy of the He + ion. The He + ion-induced detrapping cross-sections have been evaluated by analyzing the experimental data with mass balance equations including elementary processes such as detrapping, trapping and local molecular re-combination between an activated hydrogen atom and a trapped one. The elastic displacement collisions with energetic carbon recoils produced by He + ion bombardments are dominant for the detrapping of hydrogen in the range of the incident energies.

Behavior of hydrogen implanted into Si-implanted SiO 2

We applied the elastic recoil detection method to the in situ measurement of the hydrogen behavior in Si-implanted SiO 2 samples, where annealing in hydrogen environment increases photoluminescence efficiency. Dominant hydrogen trap sites changed depending on implantation conditions. In samples annealed at room temperature, hydrogen seems to be trapped forming vacancy–H (V–H) and Si–H bonds. The thermal annealing of the high-dose Si-implanted SiO 2 samples up to a temperature of 1173 K changes defects into tight hydrogen trapping of Si–H bond in conflict with results obtained at a low dose implantation. Annealing at 1343 K grows Si nanocrystals, and hydrogen seems to be trapped at the interface of Si nanocrystal/SiO 2 matrix. However, a result of high-dose implantation of Si up to 6×10 17 cm −2 showed that a large part of hydrogen is trapped as self-induced V–H complexes formed inside the crystals instead of the trap at interface.

Hydrogen analyses of titanium hydride by ERD and NRG methods

The hydrogen concentrations in δ-phase titanium hydrides (δ-TiH x : 1.6< x<2.0), prepared by means of Sieverts apparatus, have been measured by means of elastic recoil detection (ERD) and neutron radiography (NRG) methods which are non-destructive hydrogen analyses. It is concluded that the hydrogen concentration in TiH x is determined by the ERD measurement with an accuracy of ±0.05. The hydrogen concentrations in the hydrides with various H/Ti ratios have been also estimated by combining the NRG data with a general Monte Carlo neutron-particle transport code, where the neutron scattering process during the NRG measurement is simulated.

Nano-diamond films deposited by direct current glow discharge assisted chemical vapor deposition

Continuous carbon films are deposited by the direct current (DC) glow discharge assisted chemical vapor deposition method using a hydrogen–methane gas mixture. As a result of the DC-glow discharge–surface interaction, the substrate is covered by a film whose properties are strongly affected by the glow discharge and substrate conditions. It was found that under appropriate combination of the experimental parameters, a nano-sized carbon composite film containing a predominating diamond phase can be produced. The properties of the deposited carbon films were studied as a function of experimental conditions by a number of complementary techniques. The composition of the films was assessed by electron spectroscopy and the elastic recoil detection method; the morphology and structure of the films were investigated by high-resolution scanning and transmission electron microscopy (HR TEM and HR SEM). Particular attention was paid to the studies of chemical bonding of the deposited materials. For this purpose, the near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy and electron energy loss spectroscopy (EELS) techniques were used. The average film density was measured by Rutherford backscattering spectrometry. Electron diffraction, NEXAFS and EELS measurements render unambiguous evidence of diamond phase formation by the DC-glow discharge process. The nano-size dimensions of the deposited material were determined from both HR-SEM and -TEM measurements. The critical role of substrate temperature for the formation of nano-diamond particles was established based on the spectroscopic and microscopic results. Hydrogen adsorption/desorption appears to be a critical factor in this process.

反跳粒子検出法，陽電子消滅測定法による黒鉛中の水素，重水素と欠陥の研究

Behavior of deuterium atoms implanted in graphite has been investigated by ERD (elastic recoil detection) method and the defect behavior has also been studied by positron annihilation method. It was found that diffusion of deuterium atoms shows a significant anisotropy, i.e., very high diffusivity along the direction parallel to the basal plane and very low diffusivity along the direction perpendicular to the basal plane. Deuterium atoms are considered to be trapped at the boundaries between adjacent crystallites and the sites of radiation induced defects and are released from the specimen through three stages in the isochronal annealing process depending on the depth of the trapping potential. The isochronal annealing curve of the positron lifetime for HOPG irradiated with electrons at 77 K can be divided into two stages, i.e., below 1200°C and above 1200°C. In the former the increase of positron lifetime corresponding to the growth of interstitital type loops is observed and in the latter that corresponding to the growth of vacancy type loops (and also to interstitial type loops) is observed. Positron lifetime calculation for a vacancy and vacancy clusters was made and the comparison with the experimental results was also made to clarify the fundamental aspects of radiation induced defects in graphite.

Hydrogen absorption behavior into boron films by glow discharges in hydrogen and helium

Abstract Hydrogen absorption behavior into boron films deposited on graphite and stainless steel (SS) has been studied. Hydrogen absorption into a H-depleted boron film was investigated during a hydrogen glow discharge with pressure drop measured by a diaphragm gauge. It was found that, after strong but short time absorption at initial phase, hydrogen atoms were slowly (a few percents of injected H atoms) but continuously absorbed without saturation up to 3 h, which was not observed with SS liner without boron coating. Hydrogen atoms were not only desorbed but also implanted into the film during a helium glow discharge and thus, hydrogen atoms were accumulated in the film when H 2 and He discharges were repeated alternately. These accumulation effects enhanced by ions from the glow discharge were investigated quantitatively and the effect of bombarding ion species (H + or He + ) was discussed. Depth profile of H atoms was measured by elastic recoil detection (ERD). The density of only near surface region was increased when the hydrogen atoms were injected. Longer time exposure to H 2 discharge resulted in increase in surface density and shift of the peak position to deeper into the film. These results were explained by diffusion of H atoms due to ion impact into the films with keeping its saturation level if we consider resolution of ERD method of 25 nm. From the results, applicability of boron film as protection layer of tritium permeation is discussed.

Hydrogen absorption behavior into boron films by glow discharges in hydrogen and helium

Hydrogen absorption behavior into boron films deposited on graphite and stainless steel (SS) has been studied. Hydrogen absorption into a H-depleted boron film was investigated during a hydrogen glow discharge with pressure drop measured by a diaphragm gauge. It was found that, after strong but short time absorption at initial phase, hydrogen atoms were slowly (a few percents of injected H atoms) but continuously absorbed without saturation up to 3 h, which was not observed with SS liner without boron coating. Hydrogen atoms were not only desorbed but also implanted into the film during a helium glow discharge and thus, hydrogen atoms were accumulated in the film when H 2 and He discharges were repeated alternately. These accumulation effects enhanced by ions from the glow discharge were investigated quantitatively and the effect of bombarding ion species (H + or He +) was discussed. Depth profile of H atoms was measured by elastic recoil detection (ERD). The density of only near surface region was increased when the hydrogen atoms were injected. Longer time exposure to H 2 discharge resulted in increase in surface density and shift of the peak position to deeper into the film. These results were explained by diffusion of H atoms due to ion impact into the films with keeping its saturation level if we consider resolution of ERD method of 25 nm. From the results, applicability of boron film as protection layer of tritium permeation is discussed.

Control of discharge conditions to reduce hydrogen content in boron films coating

Boronization at near room temperature has been performed in plasma processing teststand (PPT) by using a 5% diborane gases B 2H 6 in He on electrically floating or cathode potential Al samples under various DC glow discharge conditions as a function of power or total gas pressure. The hydrogen concentration was analyzed by using elastic recoil detection method (ERD) and a new modified normalizing technique with Rutherford back scattering (RBS). Results showed that a high growth rate of film formation and floating surface were effective in reducing hydrogen concentration in B films. This result was in good agreement with earlier measurements of H with flash filament (FF) desorption method. In particular it was presumed from the experiments that the H B ratio was reduced by decreasing energetic ions but increasing radicals for B film formation.

Investigation of the elements depth profiles in surface layers of glass modified by ion beam assisted deposition

Depth profiles of Ti, O, N, C, H, Cu and substrate atoms (Na, Ca, Si and O) were investigated in near-surface layers of glass. Rutherford Backscattering Spectrometry (RBS) of 4He+ ions, non-Rutherford and resonant elastic Backscattering Spectrometry (BS) of 4He+ and 1H+ ions (reactions 16O(p, p)16O, 28Si(p, p)28Si, 12C(p, p)12C, 14N(p, p)14N and 16O(4He, 4He)16O) and method of Elastic Recoil Detection (ERD) of 1H+ using 2.4 MeV 4He+ analysis beam were applied in complex for the elements depth profiling. The sample was modified by using the new ion source TAMEK. The source operated in the regime of ion beam assisted deposition (IBAD) of wide aperture (300 cm2) Ti ions flow (ion implantation at average beam energy ≈ 120 keV and simultaneous deposition of the same ions at energy 100 eV) in pulse mode. The sample preparation was carried out in a nitrogen atmosphere with the pressure of about 3 × 10−4 Torr. Rate of dose accumulation at the grounded target was ≈ 1016ioncm2 min. Surface temperature of the sample was less than 50°C during IBAD treatment. Two characteristic areas were indicated in the modified layer: the mutual mixed Ti-glass layer and the coating with Ti, O, N, C, H and Cu composition. Total thickness of modified Ti-glass layer was found to be ≈ 400 nm.