Browsing by Author "Martin, JW"

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    Analysis of compound semiconductor materials using heavy ion recoil spectrometry
    (Australian and New Zealand Institutes of Physics, 1994-11-09) Walker, SR; Johnston, PN; Bubb, IF; Studd, W; Cohen, DD; Dytlewski, N; Hult, M; Whitlow, HJ; Zahring, C; Östling, M; Andersson, M; Martin, JW
    Heavy Ion Recoil Spectrometry has been used to examine various semiconductor material systems which cannot easily be studied using convensional ion beam techniques such as RBS. The technique enables the determination of seperate energy spectra for individual elements. This enables it to be used in many situations where RBS is inappropriate due to the superimposition of signals in the backscattering spectrum. We have employed Recoil Spectrometry to study; light element impurity concentrations, stoiciometry and metalisation contact systems for various compound semiconductor materials.- The experiments were performed at the ANTARES (TN Tandem) accelerator facillity at Lucas Heights using 61-91 MeV 12?I ions jn e incident " ' i ions cause nuclei of the sample to recoil following Rutherford scattering. The recoiling target nuclei are then analysed by a Time Of Flight and Energy (TOF-E) detector telescope composed of two timing pickoff detectors and a surface barrier (energy) detector. From the time of flight and energy, the ion mass can be determined and individual depth distributions for each element can be obtained.
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    An elastic recoil time of flight spectrometer for material analysis
    (Australian and New Zealand Institutes of Physics, 1994-02-10) Martin, JW; Cohen, DD; Dytlewski, N; Russell, GJ; Garton, D
    A heavy ion elastic recoil time of flight (ERTOF) spectrometer has been built on the ion beam analysis (1BA) beam line of the 8 MV tandem particle accelerator at the Australian Nuclear Science and Technology Organisation (ANSTO). The spectrometer consists of two electrostatic mirror time detectors, as described in the literature by Whitlow et. al. and Busch et al. at the forward scattering angle of 45°, and an ion-implanted surface barrier energy detector. The flight length of 750mm gives a typical timing resolution of a few hundred pico-seconds. The use of high energy heavy ions in recoil spectrometry is ideally suited to the analysis of light ions in heavy matrices, though the analysis of recoil spectra presents some ambiguity due to the overlap of individual depth profiles. An HRTOF spectrometer, with incident 77MeV 127 I 10+ as designed here, allows individual depth profiling of most elements contained within the matrix, even those in close proximity in the periodic table, therefore providing an unambiguous profile and greater certainty in sample analysis. This paper will outline the design and principles of the ERTOF spectrometer built on the IBA beam line at ANSTO. The application of this technique to materials analysis and such examples as YBCO superconductors and AlGaAs semiconductors systems will also be presented.
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    A study of transition metal implanted single crystal YBa2 Cu3 O7-δ
    (Australian and New Zealand Institutes of Physics, 1994-02-10) Martin, JW; Russell, GJ; Cohen, DD; Evans, PJ; Hartmann, A
    The modification of materials by ion-implantation is a method by which the structure and properties of a material can be altered in a controlled fashion and the study of these modified structures can lead to a better understanding of the parent material. The application to the Held of high temperature superconductors has been present ever since the discovery of the new oxides. In this study, high quality single crystal YBa2 Cu3 O7-δ was implanted separately with several different transition metal ions. The implantation was carried out using a metal vacuum vapour arc (MEVVA) ion source operated at 30kV with an approximate dose of ixlO17 ions/cm2 being applied. The resulting crystals were subsequently annealed in two separate anneal cycles in an oxygen atmosphere at 55O°C for a total of 108 hours. The sample analysis techniques involved the use of Rutherford backscattering spectroscopy (RBS), at both 2 and 3.07MeV, a.c. susceptibility measurements, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) for compositional, superconductivity, crystal structure and bonding analysis respectively. This paper will report on the results of this study which have shown that the implantation of nickel increased the rate of oxygenation in the near surface region, obtaining a transition temperature of 92°K after only 108 hours anneal time, whereas the implantation of iron was deleterious with a transition temperature of only 78°K reached after the same anneal cycles.