Browsing by Author "Pretorius, R"

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    Growth and characterisation of thin film superconductors on oxides, silicon and silicides
    (1994) Naidoo, R Y; Pretorius, R; Comrie, Craig M
    High Tc thin film superconductors are of great interest because of their potential applications, particularly in the microelectronics field. A successful superconductor microelectronic technology depends both on the ability to grow good quality superconducting thin films, and the need to incorporate these films into multilayer semiconductor devices. In this work the growth and characterisation of high Tc Y₁Ba₂Cu₃O₇ films by inverted cylindrical magnetron sputtering and pulsed ruby laser ablation on oxides, silicon and silicides is investigated. The inverted cylindrical magnetron sputter system has been effectively used to counter the problem of negative ion re-sputtering found in sputter deposition of oxide films. The optimal growth conditions for both these techniques have been determined. Rutherford backscattering spectrometry is used to obtain thickness and stoichiometry information, while X-ray diffraction gave phase and orientational data. Ion channeling was used for structural analysis and Auger electron spectroscopy was used to determine the homogeneity of the films.
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    Marker studies of nickel silicide formation
    (1988) McLeod, John Edward; Comrie, Craig M; Pretorius, R
    Atomic diffusion during the solid state formation of thin films of nickel silicides (Ni2Si and NiSi) from nickel and amorphous silicon has been investigated using 31Si radioactive tracer and inert marker techniques. Samples were prepared by vacuum deposition of thin films of nickel and silicon, followed by thermal annealing to effect silicide growth. The radioactive tracer investigation of Ni2Si showed nickel to be the diffusing species during silicide growth. Sharply defined Ni2si* profiles of 100% radioactive concentration at the sample surface were - obtained. The results are compared with previous results in which the profiles were more spread out and of lower surface concentration. The radioactive tracer investigation of NiSi formation showed that nickel is also the diffusing species during second phase growth. The NiSi * layer was found to be of 100% concentration. Some spreading of the activity profile near the NiSi/NiSi* interface was observed. The results were consistent with previous 31Si tracer work on NiSi formation and also with the present Ni * 2Si results. The inert marker investigation used an ultra-thin (5-10 A) continuous layer of Mo or Ta to monitor atomic movement during silicide growth. The results confirmed nickel to be the diffusing species during the growth of both phases. These results are in excellent agreement with previous inert marker studies of nickel silicide growth.