Browsing by Author "Motta, N"

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    Low temperature CO sensitive nanostructured WO3 thin films doped with Fe
    (Elsevier Science BV, 2012-02-20) Ahsan, M; Tesfamichael, T; Ionescu, M; Bell, J; Motta, N
    Nanostructured tungsten oxide thin film based gas sensors have been developed by thermal evaporation method to detect CO at low operating temperatures. The influence of Fe-doping and annealing heat treatment on microstructural and gas sensing properties of these films have been investigated. Fe was incorporated in WO3 film by co-evaporation and annealing was performed at 400 degrees C for 2 h in air. AFM analysis revealed a grain size of about 10-15 nm in all the films. GIXRD analysis showed that as-deposited films are amorphous and annealing at 400 degrees C improved the crystallinity. Raman and XRD analysis indicated that Fe is incorporated in the WO3 matrix as a substitutional impurity, resulting in shorter O-W-O bonds and lattice cell parameters. Doping with Fe contributed significantly toward CO sensing performance of WO3 thin films. A good response to various concentrations (10-1000 ppm) of CO has been achieved with 400 degrees C annealed Fe-doped WO3 film at a low operating temperature of 150 degrees C. © 2012, Elsevier Limited
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    Quasi free-standing graphene growth on FIB-Patterned 3C-SiC nanostructures
    (Australian Institute of Physics, 2018-01-30) Amjadipour, M; Tadich, A; MacLeod, J; Lipton-Duffin, J; Iacopi, F; Motta, N
    There is a growing body of literature that recognizes the potential of graphene for use in electronics. However, graphene’s lack of bandgap challenges its remarkable range of applications. Theoretical work suggests that a bandgap might be opened in graphene through quantum confinement, for example in graphene nanoribbons. Thermal decomposition of SiC has proven to be an excellent method to grow transfer-free wafer-scale graphene. Growing graphene on SiC thin films on Si is a cheaper alternative to the growth on bulk SiC. In this research we attempt to manipulate the SiC substrate dimension to grow graphene over nanostructures and use hydrogen intercalation to produce quasi free-standing graphene. SiC mesas have been fabricated by patterning SiC/Si substrates using Focused Ion Beam (FIB) milling. Hydrogen intercalation procedure has been employed at 600 °C to fabricate free-standing graphene on the structures. Synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) with core-level photoelectron spectroscopy (PES), scanning tunnelling microscopy (STM), scanning electron microscopy (SEM), and Raman spectroscopy were used to investigate the process. Our result indicates the possibility of growing free-standing epitaxy graphene over SiC nanostructures. However, more research is needed to better understand the impact of patterning procedure on the graphene growth and decrease the damage caused by milling process.