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Abstract: In this work a careful manual analysis of Rutherford backscattering spectrometry spectra is discussed to determine the InN content of Al1− x In x N thin films grown on GaN buffer layers. The main source of error arises from the fact that the low signal of Al is superimposed to the high signal of Ga from the GaN buffer layer. The uncertainties in the derived InN fraction are discussed. Furthermore, it is shown that channelling effects only have a minor influence on the compositional analysis of the studied films although they can significantly reduce the count rate and distort the shape of the spectra. [Copyright &y& Elsevier]

Abstract: We report an important extension to the DataFurnace code for Ion Beam Analysis which allows users to simultaneously and self-consistently analyse Rutherford (RBS) or non-Rutherford (EBS) elastic backscattering together with particle-induced gamma-ray (PIGE) spectra. We show that the code works correctly with a well-known sample. Previously it has not been feasible to self-consistently treat PIGE and RBS/EBS data to extract the depth profiles. The PIGE data can be supplied to the code in the usual way as counts versus beam energy, but the differential cross-sections for the PIGE reaction are required. We also compared the results obtained by the new routine with high resolution narrow resonance profiling (NRP) simulations obtained with the stochastic model of energy loss. [Copyright &y& Elsevier]

Abstract: The IBA DataFurnace (NDF) is a general purpose program for analysis of IBA data. It currently includes Rutherford backscattering (RBS), elastic (non-Rutherford) backscattering (EBS), elastic recoil detection analysis (ERDA), non-resonant nuclear reaction analysis (NRA), and particle induced X-ray emission (PIXE). Here we discuss recent developments in the advanced physics capabilities implemented in NDF, supported by advanced algorithms. Examples of real life hard cases are given that illustrate the issues discussed. [Copyright &y& Elsevier]

Abstract: There is strong current interest in Förster resonant energy transfer (FRET) from a semiconductor quantum well (QW) to an overlayer of another luminescent material. The FRET process becomes efficient when the two materials are placed at interaction distance of a few nanometres. The additional requirement of large spectral overlap between the energy donor and acceptor can be satisfied by combinations of InGaN/GaN QWs (as donors) and overlayers of either light-emitting polymers or nanocrystalline semiconductor quantum dots (as acceptors), both of which can be tailored to have high absorption in the QW emission region. Here we study a set of custom grown InGaN/GaN single QW samples, in which the GaN cap layer thickness was varied to modulate the FRET rate in hybrid structures. We used high-resolution grazing angle RBS experiments to determine the GaN cap layer thickness, varied from 2 to 12nm, which controlled the interaction distance between the QW and the coupled luminescent medium in hybrid structures. The very careful experiments and data analysis are discussed in detail, including a consideration of the errors in the final results obtained. An example of the use of the measured thickness values to confirm the dominance of sheet-to-sheet dipole–dipole interactions in QW-polymer hybrid structures is discussed. [Copyright &y& Elsevier]

Abstract: Analysis of RBS and ERDA data relies first and foremost on knowledge of the relevant stopping power and scattering cross-sections. Scattering cross-sections in the non-Rutherford region are often used for enhanced sensitivity to light elements, or for instance in 4He-ERDA measurement of hydrogen. Accurate experimental cross-section values in the energy and scattering angle regions of interest to IBA are thus essential to much analysis work. We developed a new method to determine scattering cross-sections experimentally, which consists in collecting many RBS spectra at different energies, and analysing them taking the cross-sections as fitting parameter. High quality simulations of resonances is essential. A Bayesian inference analysis leads not only to the cross-section curve that best fits the data, but also leads to confidence limits on the results obtained. We apply the method to several (p,p) resonances, and compare them to the literature experimental and evaluated values. [Copyright &y& Elsevier]

Abstract: In elastic backscattering spectrometry, the shape of the observed spectrum due to resonances in the nuclear scattering cross-section is influenced by many factors. If the energy spread of the beam before interaction is larger than the resonance width, then a simple convolution with the energy spread on exit and with the detection system resolution will lead to a calculated spectrum with a resonance much sharper than the observed signal. Also, the yield from a thin layer will not be calculated accurately. We have developed an algorithm for the accurate simulation of backscattering spectra in the presence of sharp resonances. Albeit approximate, the algorithm leads to dramatic improvements in the quality and accuracy of the simulations. It is simple to implement and leads to only small increases of the calculation time, being thus suitable for routine data analysis. We show different experimental examples, including samples with roughness and porosity. [Copyright &y& Elsevier]

Developments in the analytic model for double scattering in Rutherford backscattering spectra are presented. It is shown that, in grazing angle of incidence spectra of thin films, the main contribution to the low energy tails comes from particles that after the first collision have a path nearly parallel to the surface of the sample. Thus collisions with small scattering angle must be included, since they are the only way of achieving such paths. In bulk samples, these trajectories must also be included. Particle loss as the beam enters the sample, as well as angular dependent screening, are taken into account in the model developed. The effect of lateral spread due to multiple scattering is considered, and its influence in the double scattering spectrum is calculated. It is found to be important in the measurement of ultra-thin films in grazing geometry. [Copyright &y& Elsevier]

In this work automated fitting of Rutherford backscattering (RBS) data including the effect of roughness is performed, by calculating the effect of roughness on the apparent energy resolution as a function of depth. This depends on the exact type of roughness, and three different models have been implemented: inhomogeneous layer thickness, corrugated sample, and rough substrate surface. Full automated fitting can be performed including one, or more, of the models, with the roughness parameters (e.g. standard deviation of the thickness of any number of layers), as well as the sample structure, as fitting parameters. The code is applied to the system substrate/Re 50 A˚/(Co 20 A˚/Re 5 A˚)16, which had been studied before by other methods. The results are excellent, providing a new tool for RBS data analysis. [Copyright &y& Elsevier]

Five elements (Ti, Fe, Co, Er and Au) were implanted in sapphire to fluences between 8×1013 and 5×1017 at/cm2, and energies between 200 and 800 keV. We used Rutherford backscattering to determine the dose and depth of the implanted elements. The data analysis is performed using an artificial neural network (ANN). Here we report a generalisation of previous works where ANNs were successfully applied for specific implantations such as Er in sapphire and Ge in Si. We have now developed a code that it is able to analyse data from implantations of any element with Z between 18 and 83 into sapphire. Although this problem is considerably more complex than single-system ANNs, the ANN developed produced excellent results when applied to experimental data. We discuss the reliability of the ANN and its applicability to the analysis of large batches of implanted samples. [Copyright &y& Elsevier]

For some nuclei the (non-Rutherford) elastic scattering cross-section has a fine structure with a typical width of the resonances of 1–10 keV. It is shown that bulk sample backscattering spectra can be calculated correctly in these cases only if these are carefully taken into account. The proton elastic backscattering (EBS) spectrum from bulk aluminium was measured just above the interval 1.35–1.75 MeV where a strong resonance structure in the 27Al(p,p0)27Al cross-section has a relatively high density. Different sets of the Al cross-section data were employed in the simulation: the high resolution proton resonance measurement results retrieved by R-matrix calculations and experimental data obtained later especially for use in IBA. These data sets were consistent, but the latter sets did not resolve the fine structure of the cross-section. The simulations reproduce the spectra well only for the high resolution data: that is, EBS spectra can be simulated provided that the scattering cross-section include all the detail of the fine structure. [Copyright &y& Elsevier]

We present an algorithm based on artificial neural networks (ANNs) able to determine optimised experimental conditions for Rutherford backscattering (RBS) measurements of Ge-implanted Si. The algorithm can be implemented for any element implanted into a lighter substrate, and can be extended to other ion beam analysis techniques. It is a push-button black box, and does not require any human intervention. It is suited for automated control of an experimental setup, given an interface to the relevant hardware. Once the experimental conditions are optimised, the algorithm analyses the final data obtained, and determines the desired parameters. The method is hence also suited for automated analysis of the data. [Copyright &y& Elsevier]

GaN epitaxial films were grown on silicon substrates by molecular beam epitaxy under different conditions. Some of the films were doped with the rare earths (RE) Er, Eu or Tm during the growth, and were studied regarding its composition and crystalline quality. The Rutherford backscattering/channelling and heavy ion elastic recoil detection techniques were combined in order to get information on the depth distribution of all the elements present in the films. The results show that the single crystalline quality of the films improves with increasing substrate temperature and Ga flux. For these conditions the Ga concentration is the one expected for a stoichiometric film. A decrease of the Ga flux or increase in the RE cell temperature allows an increase of the concentration of the RE incorporated during the growth. The light impurity present in all the films studied, within our detection limits, was hydrogen. The angular scans along the 〈0 0 0 1〉 reveal that a fraction of the RE is incorporated into regular lattice sites of the wurtzite structure of GaN. Moreover, the optical properties of the films correlate well with the crystalline quality and the Eu doped samples show an intense red luminescence at room temperature. [Copyright &y& Elsevier]

Examines the application of combinatorial optimization simulated algorithm to the analysis of Rutherford backscattering (RBS) data. Presentation of the particularities of the algorithm; Calculation of the theoretical RBS spectrum; Indication of the simulated annealing algorithm.

Abstract: This paper reports on the advantage of using artificial neural networks (ANNs) to analyze large sets of real-time Rutherford backscattering spectrometry (RBS) data. Real-time RBS, i.e. collecting RBS spectra at periodic time intervals during a thermal treatment, probes the full response of a thin film to the annealing in situ. Although very valuable insights can be gained by this technique, the time-consuming analysis of the vast amount of RBS spectra acquired during real-time RBS measurements has so far prevented the widespread use of real-time RBS. Setting up an ANN is quite an intensive process as well, but once trained, these ANNs can handle the analysis of large data sets practically instantaneously. As such, the beneficial combination of real-time RBS and ANN analysis forms a perfect synergy. In this test case, a network was trained and applied to analyze the Ni silicide growth during annealing of a thin 80nm Ni film on Si(100). The ANN performance was validated by comparing the ANN results with the conventional analysis performed on the same data set. [Copyright &y& Elsevier]

Abstract: Particle induced X-ray emission (PIXE) is now routinely used for analyzing paint layers. Various setups have been developed to investigate the elemental composition of samples or wood/canvas paintings. However, the characterisation of paint layers is difficult due to their layered structure and due to the presence of organic binders. Also, standard PIXE codes do not support the quantitation of depth profiles in the general case. Elastic backscattering (both Rutherford and non-Rutherford) is usually used in ion beam analysis to determine depth profiles. However, traditional data processing using iteration between standard PIXE codes and particle scattering simulation codes is very time consuming and does not always give satisfactory results. Using two PIXE detectors and one particle detector recording simultaneously in an external beam geometry, we have applied a global minimisation code to all three spectra to solve these depth profiles self-consistently. This data treatment was applied to various different cases of paint layers and we demonstrate that the structures can be solved unambiguously, assuming that roughness effects do not introduce ambiguity. [Copyright &y& Elsevier]

Abstract: The Rutherford backscattering spectroscopy (RBS) and particle induced X-ray emission (PIXE) techniques can be used to obtain complementary information about the characteristics of a sample but, traditionally, a gap has separated the available computer codes for analyzing data from each technique, being hard to simultaneously analyze data from the same sample. The recent development of a free and open source library, LibCPIXE, for PIXE simulation and analysis of arbitrary multilayered samples, has permitted to integrate this technique into the DataFurnace code which already handles many other IBA techniques such as Rutherford and non-Rutherford backscattering, elastic recoil detection and non-resonant nuclear reaction analysis. The fitting capabilities of DataFurnace can therefore now be applied to PIXE spectra as well, including the Bayesian inference analysis and the simultaneous and coherent fitting of multiple spectra from different techniques. Various examples are presented in which the simultaneous RBS and PIXE analysis allows us to obtain consistent results that cannot be obtained by independent analysis of the data from each technique. [Copyright &y& Elsevier]

Abstract: The hyperfine field at 181Ta lattice sites in a nanostructured HfO2 thin film doped with Fe was studied using Rutherford Backscattering Spectrometry and Perturbed Angular Correlation techniques. The 409nm Hf film was deposited by Electron Beam Evaporation on a silicon substrate. The radioactive 181Hf ions were produced by neutron activation of the nanofilm in the Brazilian Research Reactor (IPEN IEA-R1) by the reaction 180Hf(n,γ)181Hf. These studies provided an excellent opportunity to obtain unique information regarding local arrangement of the grains, structure, phase transformations of nanoparticles and interfaces of nanostructured materials and the thin film. [Copyright &y& Elsevier]

Abstract: Reactive magnetron sputtering was used to deposit titanium oxycarbide thin films. The overall set of results showed that the oxygen flow rate, and thus the composition of the atmosphere in the deposition chamber, controls the composition of the titanium oxycarbide thin films obtained by reactive sputtering. Rutherford Backscattering Spectroscopy analysis revealed the existence of three major types of films, indexed to their particular composition ratios. A detailed study by X-ray photoelectron spectroscopy was carried out in order to characterize the evolution of the Tilyph name="sbnd" />O and Cnduced by the increase of the oxygen partial pressure, which was found to be closely related with the different zones of composition that were suggested. Micro-Raman spectroscopy and X-ray diffraction measurements allowed describing the complex nature of the film structure, namely in what concerns different phases and their evolution, texture phenomena and grain size evolution as a function of the particular composition and film types (different zones). Electrical conductivity revealed a transition from a metallic to a semi-conducting behavior as a function of the oxygen concentration in the films, in good agreement with the different zones that were suggested. Similarly, optical properties supported this gradual change and for oxygen contents higher than 67at.%, the films exhibited typical reflectance of insulator materials (interferences) in the UV, visible and near IR regions. [Copyright &y& Elsevier]

Abstract: The effects of annealing temperature on nanocrystalline sputter-deposited Ni thin films (500nm) deposited on WC–Co (4wt.%) were investigated. Special attention was focused on quantitative evaluation of residual stress and Ni diffusion into the WC–Co, after heat treatment, from 873 to 1273K. The estimated level of residual stress, as measured by X-ray diffraction, is around −1.3±0.1GPa for the as-deposited film, whereas after annealing at 1273K it decreases significantly. Atomic force microscopy shows that high annealing temperature results into an exponential increase of the roughness. An intermixing between the nanocrystalline Ni and the Co from WC substrate occurs, as it is revealed by quantitative depth-resolved Rutherford backscattering spectrometry analysis and also supported by X-ray photoelectron spectroscopy. We ascribe a significant stress relief with the increasing annealing temperature to the diffusion process. The understanding of this process is particularly important in WC–Co parts with the surface treated with Ni in order to improve the maximum surface service temperature. [Copyright &y& Elsevier]

Abstract: We have previously developed artificial neural networks (ANN) dedicated to the analysis of RBS spectra. One of the limitations of the ANNs so far developed was that one single spectrum could be analysed from each sample. When more than one spectrum is collected, each had to be analysed separately, leading to different results and hence reduced accuracy. Here we develop an ANN that can analyse multiple Rutherford backscattering and elastic recoil detection analysis spectra collected from the same sample. The ANN is applied to a simple case, namely the composition of TiNOH films. We report on the optimisation of the network architecture and training. We show that the information present in the different spectra can be integrated to produce a highly accurate final result. [Copyright &y& Elsevier]

In multilayered Ti0.4Al0.6N/Mo coatings, a strengthening effect can be obtained by using alternate layers of materials with high and low elastic constants. This behaviour requires a multilayer periodicity below a certain value in order to reduce dislocation motion across layer interface. Below this critical period, in most cases the hardness decreases as the period decreases. The multiple interfaces have an important role on this behaviour, working as stress relaxation areas and preventing crack propagation, influencing the mechanical properties of the system. Understanding the origin of these effects requires knowledge of the interface structure, where the interfacial roughness is of prime importance. We used Rutherford backscattering to study roughness in a quantitative way, and developed an artificial neural network algorithm dedicated to the analysis of the data. The results compare very well with previous TEM and AFM data. [Copyright &y& Elsevier]