Browsing by Author "Holland, AS"

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    In situ micro-Raman analysis and x-ray diffraction of nickel silicide thin films on silicon.
    (Elsevier, 2009-01) Bhaskaran, M; Sriram, S; Perova, TS; Ermakov, V; Thorogood, GJ; Short, KT; Holland, AS
    This article reports on the in situ analysis of nickel silicide (NiSi) thin films formed by thermal processing of nickel thin films deposited on silicon substrates. The in situ techniques employed for this study include micro-Raman spectroscopy (μRS) and X-ray diffraction (XRD); in both cases the variations for temperatures up to 350°C has been studied. Nickel silicide thin films formed by vacuum annealing of nickel on silicon were used as a reference for these measurements. In situ analysis was carried out on nickel thin films on silicon, while the samples were heated from room temperature to 350°C. Data was gathered at regular temperature intervals and other specific points of interest (such as 250°C, where the reaction between nickel and silicon to form Ni2Si is expected). The transformations from the metallic state, through the intermediate reaction states, until the desired metal–silicon reaction product is attained, are discussed. The evolution of nickel silicide from the nickel film can be observed from both the μRS and XRD in situ studies. Variations in the evolution of silicide from metal for different silicon substrates are discussed, and these include (1 0 0) n-type, (1 0 0) p-type, and (1 1 0) p-type silicon substrates. © 2009, Elsevier Ltd.
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    Microstructural and compositional analysis of strontium-doped lead zirconate titanate thin films on gold-coated silicon substrates
    (Cambridge University Press, 2009-02) Sriram, S; Bhaskaran, M; Mitchell, DRG; Short, KT; Holland, AS; Mitchell, A
    This article discusses the results of transmission electron microscopy (TEM)-based characterization of strontium-doped lead zirconate titanate (PSZT) thin films. The thin films were deposited by radio frequency magnetron sputtering at 300°C on gold-coated silicon substrates, which used a 15 nm titanium adhesion layer between the 150 nm thick gold film and (100) silicon. The TEM analysis was carried out using a combination of high-resolution imaging, energy filtered imaging, energy dispersive X-ray (EDX) analysis, and hollow cone illumination. At the interface between the PSZT films and gold, an amorphous silicon-rich layer (about 4 nm thick) was observed, with the film composition remaining uniform otherwise. The films were found to be polycrystalline with a columnar structure perpendicular to the substrate. Interdiffusion between the bottom metal layers and silicon was observed and was confirmed using secondary ion mass spectrometry. This occurs due to the temperature of deposition (300°C) being close to the eutectic point of gold and silicon (363°C). The diffused regions in silicon were composed primarily of gold (analyzed by EDX) and were bounded by (111) silicon planes, highlighted by the triangular diffused regions observed in the two-dimensional TEM image. © 2009, Cambridge University Press