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Greg Cabailh

Research experience

2012-to date

  • Associate Professor at Université Pierre et Marie Curie (Paris 6), Paris, France. Institut des Nanosciences de Paris (INSP) – Low-dimensional oxides.
  • Research themes : model catalysts, hydroxylation and hydration, growth mode, oxide nano-objects : thin films and nanoparticles, atomic and electronic structures.

2012

  • Research Fellow (ANR Cocotrans), INSP and National Center for Scientific Research (CNRS).
  • « Transparent silver conductive layers for reinforced thermal insulation glazing and OLEDs electrodes. »

2011

  • Research assistant, Centre Interdisciplinaire de Nanoscience de Marseille (CNRS).
  • “Physical analysis of the interaction of molecules on insulator surfaces by noncontact atomic force microscopy (NCAFM).”

2009-2010

  • Research assistant, INPS, UPMC, CNRS, Paris.
  • “Morphology and reactivity of gold nanoparticles supported on crystalline oxides.”

2004-2008

  • Research assistant, London Centre for Nanotechnology, University College London.
  • “Studies of the interaction of small molecules and atoms with metal/oxide surfaces.” (NanoChemSens European research network).

2000-2004

  • Ph.D. in Physics. ‘Synchrotron radiation studies of organic/inorganic semiconductor interfaces’. Trinity College Dublin, Ireland.
  • ABSTRACT : Organic semiconductor molecules are often employed as a thin film interlayer to improve electronic and optoelectronic devices. The characterisation of the interface is thus important to understand the physical properties between the organic thin film and the inorganic semiconductor substrate. Also the orientation of the molecules within the film can be of importance. Three molecules, SnPc, MgPc and PbPc are studied on two different substrates, argon sputtered GaAs(001)-1x6 and Ge(001)-2x1. Two surface sensitive synchrotron-based techniques are used for such characterisation, soft x-ray photoelectron spectroscopy (SXPS) and near edge x-ray absorption fine structure (NEXAFS). With SXPS, the evolution of the shallow core levels of the phthtalocyanine’s central metal atom and of the substrates are studied for the clean surfaces and for different stages of growth. A fitting procedure was undertaken for better comprehension. For the clean GaAs(001) surface, As3d and Ga3d core spectra are fitted with a bulk component and one and two surface components, respectively : these spectra show no significant change when approximately one monolayer of any of three MPc molecules is deposited ; also the metal atom spectrum comprises a single component. The interaction of MPc with GaAs is described as weak. In some contrast, deposition on Ge(001) leads to changes in both substrate and deposit core spectra. The clean surface Ge3d core level spectrum is fitted with one bulk, one second layer and two surface components, the ‘up’ and ‘down’ atoms in the dimer. Upon deposition of approximately one monolayer of any three MPc molecules, approximately 50% of the ‘up’ intensity is shifted towards higher binding energy, indicative of an electron removing interaction. A corresponding electron receiving shift to lower binding energy is observed in the metal core level of two of the three molecules, SnPc and PbPc ; MgPc shows no such satellite feature. These molecules are also to be distinguished by shape : MgPc is planar while SnPc and PbPc are non-planar. It seems reasonable to attribute the two component spectrum of the latter to the two possible geometries of the metal atom in non-planar molecules with respect to the surface of the substrate (‘towards’ and ‘away’). The growth mode for the films is also deduced from the attenuation curves. SnPc has a Stranski-Krastanov growth mode whereas MgPc and PbPc have a growth close to layer-by-layer. With NEXAFS, the orientation of the molecule is investigated on both substrates. The spectra show that the films are highly orientated. At a monolayer level, the molecules are lying close to flat on the substrate surface. For thick films, it is clear that each molecule exhibits a different orientation in the films, e.g. SnPc lying close to flat to the surface whereas MgPc is ‘standing up’. The molecules exhibit the same behaviour on both substrates. By analysing the evolution of the pi* resonance intensity, the possible crystalline structures were also deduced.