N. Dytlewski

Ion beams for materials analysis

The contents of this book are: Concepts and Principles of Ion Beam Analysis; Overview of Techniques and Equipment; High Energy Ion Scattering Spectrometry; Nuclear Reactions. Ion Induced X-Ray Emission; Channeling; Depth Profiling of Surface Layers During Ion Bombardment; Low Energy Ion Scattering from Surfaces and Interfaces; Microprobe Analysis; and Critical Assessment of Analysis Capabilities.

The ANSTO high energy heavy ion microprobe

Recently the construction of the ANSTO High Energy Heavy Ion Microprobe (HIMP) at the 10 MV ANTARES tandem accelerator has been completed. The high energy heavy ion microprobe focuses not only light ions at energies of 2–3 MeV, but is also capable of focusing heavy ions at high energies with ME/q2 values up to 150 MeV amu and greater. First performance tests and results are reported here.

Multivariate analysis method for energy calibration and improved mass assignment in recoil spectrometry

Abstract Heavy ion recoil spectrometry is rapidly becoming a well established analysis method, but the associated data analysis processing is still not well developed. The pronounced nonlinear response of silicon detectors for heavy ions leads to serious limitation and complication in mass gating, which is the principal factor in obtaining energy spectra with minimal cross talk between elements. To overcome the above limitation, a simple empirical formula with an associated multiple regression method is proposed for the absolute energy calibration of the time of flight-energy dispersive detector telescope used in recoil spectrometry. A radical improvement in mass assignment was realized, which allows a more accurate and improved depth profiling with the important feature of making the data processing much easier.

Materials characterisation using heavy ion elastic recoil time of flight spectrometry

Abstract Materials characterisation by heavy ion elastic recoil time of flight spectrometry (HIERTOFS) at a forward recoil angle of 45° has been investigated using 40–110 MeV chlorine and iodine ions. Measurements are compared with a computer simulation code that evaluates the resolution components such as those due to straggling, multiple scattering, roughness and detector resolution both at the surface and at depth within the sample. The code also simulates elastic recoil time of flight spectra, which compare favourably with RBS analysis techniques. The ToF detector has a timing resolution of the order 300 ps, a mass resolution, for 30 MeV gallium recoils, of 4–5 amu and a depth resolution of 150 A at the surface. The spectrometer to date has been used to characterise such materials as YBCO thin films, GaAs structures and implanted silicon samples.

Characterization of a commercial dye-sensitised titania solar cell electrode

We have characterised a dye-sensitised nanoporous nanocrystalline titania film used in prototype photoelectrochemical solar cell production. From transmission electron microscopy the particles were seen as mixtures of tetrahedral and rhombohedral geometries with size distribution in the range between 10 and 25 nm. These particles were identified by X-ray diffraction as nanocrystals of anatase and brookite phases. The film was sensitised with a ruthenium (II) based chromophore for different times (between 0.5 and 24 h) and the penetration and coverage of the dye was studied using secondary ion mass spectroscopy. The dye was found to percolate through the whole of the titania film and was distributed uniformly. Using Rutherford backscattering, the composition of the film was determined and found to be 1 wt% Ru on maximum sensitisation. The optical properties of the dye-sensitised films were also measured which resulted in an increase of absorbance and a decrease of transmittance for dyeing times up to 8 h. Beyond this time the values remained unchanged and thus a semi-transparent film with luminous transmittance between 0.12 and 0.60 were obtained.

RBS and recoil spectrometry analysis of CoSi2 formation on GaAs

Abstract Mass and energy-dispersive recoil spectrometry has recently reached the state of development where it is possible to separately characterise Ga and As in GaAs samples. Since it is possible to simultaneously characterise several elements (light as well as heavy), e.g. C, O, Si, Co, Ga and As, the technique is suited for examining the depth distribution of metallisation contacts on GaAs. In a Swedish-Australian collaboration a recoil detector telescope was attached to a beamline of the FN tandem accelerator “ANTARES”, at Lucas Heights Research Laboratories, Australia. In the measurements presented here, 127 I 10+ at an energy of 77 MeV was employed to analyse GaAs samples with thin film overlayers — Si(220 nm)/Co(50 nm)/〈100〉-GaAs. A reference sample and samples annealed at 300 to 600°C were analysed. The measurements showed that CoSi 2 is formed during annealing at and above 500°C with no detectable reaction between the GaAs-substrate and the CoSi 2 overlayer.

Recoil spectrometry : ion accelerator based elemental characterisation of surface layers

Recoil Spectrometry covers a group of techniques that are very similar to the well known Rutherford backscattering Spectrometry technique, but with the important difference that one measures the recoiling target atom rather than the projectile ion. This makes it possible to determine both the identity of the recoil and its depth of origin from its energy and velocity, using a suitable detector system. The incident ion is typically high-energy (30–100MeV)35C1,81Br or127I. Low concentrations of light elements such as C, O and N can be profiled in a heavy matrix such as Fe or GaAs. Here we present an overview of mass and energy dispersive recoil Spectrometry and illustrate its successful use in some typical applications.

Efficiency enhancements to Monte Carlo simulation of heavy ion elastic recoil detection analysis spectra

Monte Carlo (MC) simulation can be used to simulate heavy ion elastic recoil detection analysis spectra, including the broadening and tailing effects of multiple and plural scattering, although it is very costly in terms of computer time. In this work, kinematic relationships and experimental parameters are exploited to implement efficiency improvements in the MC modeling process. For thin films, incident ions that pass through the sample without undergoing a significant scattering event need not be tracked. Ions that might generate a detectable scattered or recoiled ion are predicted by generating, in advance, the impact parameters which will define its path. Light recoiled target atoms may be dealt with in the same way. For heavy atoms, however, the probability of large angle scattering events is so high that the paths of most recoil atoms are dominated by several scattering events with large angular deflections.

INTERFACIAL REACTION STUDIES OF CR, NI, TI, AND PT METALLIZATION ON INP

Interfacial reactions between (100) InP and thin films of the transition metals Cr, Ni, Pt, and Ti have been studied. A thin layer of metal was deposited onto the InP substrates using e‐beam evaporation and parts of the samples were then subjected to heat treatment in vacuum for 30 min at several temperatures up to 500 °C. Separate characterizations of the metal, In, and P depth distributions were carried out using mass and energy dispersive recoil spectrometry. The different crystalline phases observed were determined using x‐ray diffraction. The near‐noble metals (Ni, Pt) formed ternary phases, while Ti and Cr formed phosphides. The phases formed were generally stable up to 500 °C with the major exception being Pt where the ternary phase decomposed to form PtIn2, PtP2, and Pt3In7.

Empirical characterisation of mass distribution broadening in ToF-E recoil spectrometry

Abstract The mass broadening function in mass and energy dispersive recoil spectrometry using a detector telescope for time-of-flight and energy determination, has been characterised for a number of isotopes in the range A = 12 to 197. The broadening was well described by a Gaussian function where the standard deviation is given by the empirical equation: θ A ( E, A ) = C 1 + C 2 A 3/2 E − 1 + C 3 A 2 E − 2/3 + C 4 AE 1/2