Browsing by Author "Partridge, JG"

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    Engineering titanium and aluminum oxide composites using atomic layer deposition
    (AIP Publishing, 2011-12-23) Biluš Abaffy, N; McCulloch, DG; Partridge, JG; Evans, PJ; Triani, G
    Mixed metal oxides provide a convenient means to produce coatings with tailored physical properties. We investigate the possibility of synthesizing novel coatings of mixed titanium and aluminum oxide using atomic layer deposition (ALD). Results show that ALD films were prepared with compositions ranging between Al2O3 and TiO2 having refractive indices between 1.6 and 2.4 (at λ = 550 nm) at low temperature. The microstructure and bonding environment within the films was investigated using electron microscopy and x-ray absorption spectroscopy. The films were amorphous, and the Ti and Al atoms were mixed at the atomic scale. The electrical breakdown characteristics of the films were measured and showed that films with intermediate compositions had poor leakage current properties, believed to be caused by the presence of distorted bonding configurations. This study shows that ALD can be used to deposit high quality thin films with tailored optical properties, particularly suitable for applications in which complex topographies are required. © 2011 American Institute of Physics
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    Fabrication, structural characterization and testing of a nanostructured tin oxide gas sensor
    (Institute of Electrical and Electronics Engineers (IEEE), 2009-04-07) Partridge, JG; Field, MR; Sadek, AZ; Kalantar-Zadeh, K; Du Plessis, J; Taylor, MB; Atanacio, AJ; Prince, KE; McCulloch, DG
    A nanostructured SnO 2 conductometric gas sensor was produced from thermally evaporated Sn clusters using a thermal oxidation process. SnO 2 clusters were simultaneously formed in an identical process on a Si 3 N 4 membrane featuring an aperture created by a focused ion beam (FIB). Clusters attached to the vertical edges of the aperture were imaged using a transmission electron microscope. The original morphology of the Sn cluster film was largely preserved after the thermal oxidation process and the thermally oxidized clusters were found to be polycrystalline and rutile in structure. NO 2 gas sensing measurements were performed with the sensor operating at various temperatures between 25degC and 290degC. At an operating temperature of 210degC, the sensor demonstrated a normalized change in resistance of 3.1 upon exposure to 510 ppb of NO 2 gas. The minimum response and recovery times for this exposure were 45 s and 30 s at an operating temperature of 265degC. The performance of the SnO 2 sensor compared favorably with previously published results. Finally, secondary ion mass spectrometry and X-ray photoelectron spectroscopy were used to establish the levels of nitrogen present in the films following exposure to NO 2 gas. © Copyright 2009 IEEE