Rutherford Backscattering Spectrometry Techniques Research Articles

Analysis of the composition of Ti-based thin films deposited on silicon by means of self-ion assisted deposition

The composition of Ti-based thin films deposited on silicon using a self-ion assisted deposition (SIAD) method was investigated by utilising the Rutherford backscattering spectrometry technique and RUMP simulation code. The hydrogen affinity of the coatings produced by means of SIAD was investigated using the 1H(15N, αγ)12C nuclear resonance reaction. The titanium–based films on silicon were found to have a high content of oxygen, carbon, hydrogen and substantial concentration of the substrate. Near 10% H content enrichment was found at the surface of coatings but no hydrogen enrichment at the coating–substrate interfaces was observed.

The formation of double waveguides in a KTP crystal by combining ion exchange with ion implantation

Double waveguides were produced in potassium titanyl phosphate (KTiOPO4 or KTP) by ion exchange in pure RbNO3 at 340 °C for 45 min, and subsequently ion implantation with 500 keV O ions at a dose of 1 × 1015 ions cm−2. By the prism-coupling method the guided mode spectra as well as the refractive index profiles of the ion-exchanged sample were determined. The relative value of the refractive index distribution of the ion implanted KTP sample in the z direction was simulated, which indicates the formation of double waveguides. The field pattern of the propagation light in the waveguide was collected and studied by the end-coupling method. The near-field pattern of two planar operating waveguides was observed, one upon the other. The irradiation damage as well as the Rb distribution was analysed by means of the Rutherford backscattering spectrometry technique.

Characterization of vacuum-evaporated ZnSe thin films

ZnSe thin films were deposited onto glass substrates under a vacuum of 3×10 −5 Torr by using vacuum evaporation technique. Rutherford backscattering spectrometry technique is used to measure the composition and thickness of the deposited films. The composition of the deposited films is found to be nearly stoichiometric. The X-ray diffractogram reveals a preferential orientation along (1 1 1) direction, and the structural parameters such as crystallite size, dislocation density, strain and lattice parameters are calculated, and also the effect of film thickness and substrate temperature of the deposited films was also discussed. It is observed that the crystallite size increases from 20.11 to 55.56 nm with the increase in film thickness. The X-ray diffraction (XRD) studies show that the structure of the deposited films is cubic. The crystalline nature of the deposited films is also confirmed by Raman scattering measurements. In the optical studies, optical band-gap values decrease with the increase in film thickness and substrate temperatures. In the DC conduction studies, the conduction mechanism is found to be exponential trap distribution and the results are discussed.

Bentonite colloid diffusion through the host rock of a deep geological repository

The determination of experimental data on all processes that contribute to the radionuclide (RN) migration within the barriers of a deep geological radioactive waste repository is required to evaluate the long-term behavior of the waste repository. A novel approach for the experimental estimation of bentonite colloid diffusion coefficients in granite is proposed, since no experimental data on this issue are available. The Rutherford backscattering spectrometry (RBS) technique was selected, because it is suitable for the study and the detection of gradients of heavy elements in a well-defined matrix and allows measuring diffusion coefficients on a micrometer scale. To follow the trail of the bentonite clay colloids within the granite by RBS analysis the colloids were traced with a heavy element. Complementary batch sorption experiments guaranteed that the Eu was an adequate tracer. By RBS analysis, Eu concentration gradients within the granite were clearly observed, and it was then proven that traced bentonite colloids were able to diffuse within the granite. The bentonite colloids diffusion coefficient was estimated to be ≈10 −17 m 2/s, that is a value three orders of magnitude lower than that measured for the Eu as solute (10 −14 m 2/s).

Determination of Titanium and Vanadium in Ziegler-Natta Catalysts by Inductively Coupled Plasma Atomic Emission Spectrometry

A method for the determination of Ti and V using inductively coupled plasma atomic emission spectrometry (ICP OES) in Ziegler-Natta polymerization catalysts is proposed. The concentrations of both Ti and V are efficiently determined after catalyst acid digestion with a mixture of HNO3 + HCl + HF and heating (160 degrees C for 6 h) or with 10% (v/v) H2SO4 and heating (160 degrees C for 6 h) or with 10% (v/v) H2SO4 and sonication (during 2 min). The V and Ti detection limits are 0.002% and 0.08%, respectively, using 0.20 g of catalyst sample in 50 ml. The method is validated by a comparison with the Rutherford backscattering spectrometry (RBS) technique. In this case, catalyst samples are only pressed as pellets before analyte determination. Despite the fact that both the V and Ti concentrations cannot be determined individually by means of RBS, because the atomic numbers of Ti and V are very close, the sum of the V and Ti contents is in accordance with that attained by means of ICP OES. According to scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) it is observed that the Ti distribution on the catalyst grain is not homogenous.

Luminescence and structural properties of defects in ion implanted ZnO

AbstractZnO substrates and films were intentionally implanted with rare earth and transition metal ions. The influence of the implantation and subsequent air thermal annealing treatments on the structural and optical properties of ZnO samples were studied by using Rutherford backscattering spectrometry and low temperature photoluminescence techniques. Intraionic Tm‐related emission was observed for bulk and ZnO films. Similarly, Eu and Tb‐doped ZnO films follow the same trend observed in bulk samples. No intraionic related emission was observed for Eu‐doped samples even being the ion in Zn sites and for the Tb‐doped samples ion segregation was observed for thermal annealing temperatures above 800 °C. For the Mn‐doped ZnO bulk samples the lattice recovery follows the same trend to that one observed for the Fe‐doped samples, starting near 800 °C being fully recovered at 1050 °C. Although Fe3+ was observed no intraionic Mn‐related emission was detected under the used conditions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Substrate influence on the outdiffusion of antimony dopant in monocrystalline silicon

In this work, we study the effect of silicon substrate orientation on the outdiffusion of antimony dopant. The monocrystalline Si(1 0 0) and Si(1 1 1) substrates were implanted with Sb + ions at an energy of 60 keV, to a dose of 5 × 10 15 Sb + cm −2. The recovery of radiation damage was performed with a conventional annealing treatment at 1173 K (900 °C). The analysis was carried out by means of high-resolution RBS (Rutherford backscattering spectrometry) technique using protons of 0.3 MeV energy. It was shown that Sb + ions were rejected to the surface, for both Si(1 0 0) and Si(1 1 1) samples. Moreover, it was noticed that an important quantity of antimony was lost especially for the case of Si(1 1 1) specimens. Finally, we note that several ion implantation parameters ( R p, Δ R p, dose, radiation damage) were evaluated with a good accuracy.

Sb diffusion in α-Fe

The effect of the magnetic ordering on the diffusion of Sb in α-Fe was investigated. Measurements were made in an extended temperature range: (673–1073 K), using the ion beam techniques Rutherford backscattering spectrometry (RBS) and heavy ion RBS (HIRBS) in superposed ranges of temperature. By expanding the temperature range with respect to the previous works, the Arrhenius plot shows the variation of the slope at the Curie temperature and a soft-up curvature in the ferromagnetic region. The curvature observed is well fitted by the model developed by Ruch et al. The parameter that takes into account the influence of the magnetic order in the vacancy mobility during the Sb diffusion process is quite similar to that observed in Fe self-diffusion; then, no magnetic interaction between the impurity and the matrix is postulated.

Photocatalysis in the visible range of sub-stoichiometric anatase films prepared by MOCVD

Anatase phase of titanium oxide is the most promising photocatalyst material for organic pollutant degradation. However, due to its large band gap energy (3.2 eV) it is not viable to use sunlight as an energy source for the photocatalysis activation, and so, ultraviolet (UV) radiation below the wavelength of 380 nm is required. This paper focuses on the experimental demonstration of the reduction of this large band gap energy by inducing defects in the anatase structure under the form of oxygen sub-stoichiometry. TiO 2 thin films were prepared in a metal organic chemical vapour deposition (MOCVD) reactor. The samples stoichiometry was measured by the Rutherford backscattering spectrometry (RBS) technique. Optical characterisation was also performed and the photodegradation activity in the visible range was tested using nonylphenol, which is one of the most harmful pollutants present in waste waters.

Thermodynamic stability of SiO 2 in contact with thin metal films

Solid-state compound phase formation has been investigated between thin metal films (Cu, Ir, Mo, Pt, Re, Y, Yb, and Zr) and SiO 2 substrates using Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) techniques. The thin-film couples were annealed for time periods ranging from 30 min to 3 h between 320 and 900 °C. It was found that Y, Yb, and Zr react with SiO 2 whereas Cu, Ir, Pt, Re, and Mo do not. Heats of reaction were calculated for all possible combinations of silicide and metal-oxide reaction products. Comparisons with experimental results obtained from this study and the literature show in all cases that metal–SiO 2 reactions only take place when the calculated heat of reaction is negative. This study shows that the results obtained as well as those which could be found from the literature correlate well with the electronegativity of the metal, which offers a convenient empirical method of predicting whether a metal will react with SiO 2 or not. Only metals with a Miedema electronegativity parameter less than 4.45 V reacted with SiO 2.

RBS analysis of rapidly solidified Al–Si–Ti alloy with Fe and Ni dopes

By means of Rutherford backscattering spectroscopy technique, a detailed element analysis of a rapidly solidified Al–9.6Si–0.8Ti (at%) alloy with Fe and Ni dopes has been investigated. It was found that the 0.02 μm thick surface layer of the ribbon is enriched with Si (24.0 at%) and Bi impurity (0.007 at%). Oscillations of non-uniformly Si depth distribution through the ribbon thickness were found at the ribbon surface layer (up to 0.2 μm in thickness). At the 140 °C annealing, Si atoms diffuse from the volume to the ribbon surface. Its concentration at the thin surface layer increases by 25%. At 500 °C, there is a redistribution of all alloy components. Dope elements diffuse into the ribbon volume, but Bi diffuses on the ribbon surface, reaching 0.06 at%. Si oscillations weaken, thickness of the layer in which they are detected extends to 0.4 μm.

Study of cesium diffusion in borosilicate glass by heavy ion Rutherford backscattering spectrometry

Abstract Diffusion of cesium in borosilicate glass has been studied by heavy ion Rutherford backscattering spectrometry (HIRBS) technique using 30 MeV 19F beam. Analysis of glass samples annealed at different temperatures for 12 h duration has been used to determine the activation energy of diffusion of cesium in borosilicate glass, which is considered as one of the suitable matrices for vitrification of the high level radioactive waste. Diffusion coefficients show Arrhenius behaviour in the temperature range 473–673 K. The activation energy for diffusion is found to be 22.2 ± 3.6 kJ/mol.

Characterization of electroless Au, Pt and Pd contacts on CdTe and ZnTe by RBS and SIMS techniques

Rutherford backscattering spectrometry (RBS) was applied to characterize Au, Pt and Pd contacts on II–VI semiconductor materials, CdTe and ZnTe, used as nuclear detectors. Electroless thin film depositions were prepared by changing the concentration of the reaction solution. Contrary to the deposition reaction time, it was observed that the amount of solution dilution degree had a considerable effect on increasing the thickness of the metal layer. Furthermore, PICTS electrical measurements confirmed the depth profile analysis performed by RBS and SIMS.

Damage evaluation after ion beam irradiation on polyimide films using ERD and RBS techniques simultaneously

Rutherford backscattering spectrometry (RBS) with swift ion probes is generally known as a non-destructive characterization technique for metal and semiconductor samples. On the other hand, it is also known that the technique may cause severe damages on organic insulators such as polyimide films. In this work, using the ERD (elastic recoil detection) and the RBS techniques simultaneously, the irradiation damage in a polyimide sample (Kapton-H) induced by 1.5 MeV helium ions has been evaluated by monitoring the evolution of depth profiles of hydrogen and oxygen while increasing the fluence of the primary helium ions from 1.4 × 10 14 to 2.8 × 10 15 cm −2. In the surface region of the polyimide sample, where electronic stopping is predominant, a progressive hydrogen depletion approaching 50% of the amount contained in a pristine sample has been observed. At the same time, a gradual depletion of oxygen in the near surface region of the irradiated sample has been observed.

Oxidation study of Sb + implanted Si(1 0 0) and Si(1 1 1) targets. Use of high-resolution RBS technique

High-resolution Rutherford backscattering spectroscopy (RBS) was used to study the oxidation phenomenon of antimony-implanted silicon targets. The study was carried out with respect to antimony dose and silicon target orientation. The behavior of antimony ions before and after silicon oxidation was also investigated. Prior to the oxidation process, the Si(1 0 0) and Si(1 1 1) targets were implanted to 5×10 14 or 5×10 15 Sb +cm −2 dose, at 60 keV energy. The dry oxidation of the silicon specimens, was performed under oxygen atmosphere at 900°C for 30 min. The analysis was carried out by means of RBS technique in both random and channeling modes. A beam of H + particles was used for an energy of 0.3 MeV, with a detection resolution of 2 keV. It was shown that the oxidation phenomenon was more important on Si(1 1 1) targets than on Si(1 0 0). The SiO 2 oxide layer increased with the rise in antimony ions dose. Besides, after annealing under oxygen atmosphere, a good surface damage recovery was obtained for all implanted samples. An important quantity of antimony was found to be shadowed for the case of Si(1 0 0) targets which were implanted with 5×10 14 Sb +cm −2 dose. However, for the case of 5×10 15 Sb + cm −2 dose, no shadowing of antimony ions was observed.

Study of diffusion at surface of multilayered Cu/Au films on monocrystalline silicon

Multilayered of pure gold and copper films were evaporated alternatively on (1 0 0) monocrystal silicon substrates. Annealing, in a furnace vacuum, were carried out at 200 and 400 °C for 30 min. The obtained samples were analyzed by means of Rutherford backscattering spectrometry, X-ray diffraction and scanning electron microscopy techniques. The interdiffusion of the different elements and the thermodynamic transformations at Cu/Au and Au/Si interfaces have been investigated.

Energy loss straggling of energetic 1H and 2H ions crossing polypropylene foils

An indirect transmission method as nuclear technique in precise measurement of energy loss straggling in polymer foils is presented. The details of experimental procedures related to the combination of Rutherford backscattering spectrometry and transmission technique are described. Advantages of the application of such a method in energy straggling experiments are discussed. The energy loss straggling measurements have been performed in the energy range of 900–3000 keV for protons and deuterons in thin films of polypropylene. The obtained values of energy straggling are compared to those deduced from Bohr and Bethe–Livingston theoretical predictions. This comparison was made by using Bragg’s rule as model of calculation over the investigated energy range.

Depth profiles study of n(TiN+AlN) bilayers systems by GDOES and RBS techniques

Some n(TiN+AlN) bilayers systems with n=1 and n=2 are realised by reactive magnetron cathodic sputtering. Different layers and interfacial zones are studied by glow discharge optical emission spectroscopy (GDOES) and Rutherford backscattering spectroscopy (RBS). With GDOES analysis, it is possible to check the bilayers number in each system, the total thickness of coating and the bilayer's thickness. It is also possible to compare the thickness and the roughness of interfacial zone. The higher the slope is, the less rough is the interfacial zone. A great quantity of oxygen is present, mainly in interfacial zones, when any ion bombardment is not applied. This oxygen is nearly completely eliminated, when an ion bombardment is applied during the coating's elaboration. This contamination is confirmed by the stoichiometry's determination of different layers of bilayers systems, with some RBS analyses. These RBS analyses show the interfacial roughness owing to the disagreement between the experimental points and the simulation points. To obtain a good fitting, we should simulate, in case of (TiN+AlN) systems, an additional layer, which plays the role of interfacial layer. When an ion bombardment is applied during sputtering deposition, the interfaces are well-defined and without oxygen. For 2(TiN+AlN) systems, the interfaces also appear very rough without ion bombardment.

Characterization of Si(1 1 1) crystals implanted with Sb + ions and annealed by rapid thermal processing

Monocrystalline Si(1 1 1) targets are implanted (at room temperature) with antimony ions at 120 keV energy to 5×10 14 or 5×10 15 Sb + cm −2 dose. The samples are heat treated by means of rapid thermal processing (RTP) at 1000 °C during 60 s, under nitrogen atmosphere. In this work, we report the measured evolution of the silicon surface damage and the radiation damage recovery in relation to antimony dose and RTP processing. We also study the behavior of antimony dopant into Si(1 1 1) specimens. The investigation is carried out by He + Rutherford backscattering spectrometry (RBS; operating at 1.57 MeV energy in both random and channeling modes), X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. It is shown that a good surface damage recovery is obtained for all the annealed samples. However, after RTP, a significant loss of antimony has occurred for the specimens which are implanted with 5×10 15 Sb + cm −2 dose. This suggests an antimony out-diffusion. Finally, a good morphological characterization of the specimens is provided by AFM.

Diffusion of Ta in α-Ti

The diffusion of Ta in the hcp (α) phase of high-purity Ti (99.99%) was studied at different temperatures from 911 K up to 1123 K. The Rutherford Backscattering Spectrometry (RBS) and Heavy Ion RBS (HIRBS) techniques were used to obtain the penetration profiles. The evolution of the diffusion coefficient, D, as a function of temperature follows prediction of the Arrhenius law. The activation energy of the diffusion process is (318±7)kJ/mol, similar to that corresponding to self-diffusion in α-Ti. On the other hand, the measured values of D are systematically lower than those corresponding to self-diffusion by a factor of approximately 5. This reduction could be explained by taking into account the mass difference between Ta and Ti. An increase of the diffusion coefficient was measured when the diffusion proceeds on a less pure Ti (99.9%) matrix. This increment is higher at lower temperatures.