We are studying the electronic structures of new and advanced materials. We are using synchrotron radiation to perform soft x-ray emission and absorption spectroscopy of systems like biomaterials, superconductors and transition metal compounds.

Adrian Hunt

Adrian Hunt

[adrian.hunt@usask.ca]

Education

  • University of Saskatchewan
    Saskatoon, Saskatchewan
    B.E. Engineering Physics
    April 2003
  • University of Saskatchewan
    Saskatoon, Saskatchewan
    M.Sc. Physics
    January 2007
  • University of Saskatchewan
    Saskatoon, Saskatchewan
    Ph.D. Physics
    December 2013

Current Affiliation

  • Postdoctoral Research Associate at North Carolina State University

Ph.D. Thesis

  • The many mysteries of graphene oxide

Research Projects

Graphene

Graphene has been the focus of many researchers of late because it is the first stable two-dimensional crystal ever found. Graphene is simply carbon atoms in a honeycomb lattice, and is one layer of the more familiar graphite. Prior to the discovery of graphene, two-dimensional crystals were thought to be thermodynamically unstable and therefore impossible to find. The 2D nature of graphene gives it some very interesting properties, such as metallic-like conductivity and ballistic transport over macroscopic distances. Ballistic transport results when the mean free path of conduction electrons is on the order of micrometers or longer. If the length of a conduction device is shorter than the mean free path, the electron can pass through the device without ricocheting off the lattice, hence ballistic travel. Principally, this means zero resistance. This is a highly desirable property for nanodevices, because zero resistance means no parasitic energy losses or unwanted heat generation.

Graphite oxide is an excellent material with which to begin the study of graphene, because it can function as either a precursor material of graphene, via exfoliation and chemical reduction of individual graphene oxide sheets, or as a possible organic semiconductor material. However, one of the reasons why silicon-based semiconductors have formed the bedrock of modern electronics is that the band gap of silicon is easily and predictably changed by introducing the appropriate dopant. The band gap is simply the energy difference between the uppermost valence state to the lowermost conduction band state. In short, the band gap energy is the minimum energy one has to apply to an electron in the material to make it conduct. The band gap of a semiconductor is crucial to the function of computers, because it allows for two distinct logic states: "on" and "off", or "conducting" and "non-conducting". To function in the same capacity as silicon, graphite oxide must also have a suitably tuneable band gap.

The methods with which one may make graphite oxide are numerous. In the samples of interest here, the graphite bulk is supposedly oxidized with oxygen-containing functional groups. My research focuses on determining the band gap of different samples of graphite oxide as a function of synthesis technique using soft x-ray spectroscopy techniques. The underlying factors in the physical and electronic structures of the samples that ultimately determine the band gap will also be studied in detail. The types, concentrations, and distributions of the oxidizing functional groups as functions of synthesis method are questions of particular interest in the study of this material. Only with this understanding may the capabilities of graphite oxide be fully realized.

Awards

  • NSERC CGS D3 (September 2010)

Publications

  • A. Hunt, D.A. Dikin, E.Z. Kurmaev, Y.H. Lee, N.V. Luan, G.S. Chang, and A. Moewes (2014)
    Modulation of the Band Gap of Graphen Oxide: The Role of AA-stacking
    Carbon 66, 539-545

  • T.D. Boyko, A. Hunt, A. Zerr, and A. Moewes. (2013)
    Electronic Structure of Spinel Nitride Compounds Si3N4, Ge3N4 and Sn3N4 with Tunable Band Gaps: Application to Light Emitting Diodes
    Phys. Rev. Lett. 111, 097402-1-5

  • R. J. Green, D. A. Zatsepin, A. Hunt, E. Z. Kurmaev, N. V. Gavrilov, and A. Moewes,
    The Formation of Ti-O Tetrahedra and Band Gap Reduction in SiO2 via Pulsed Ion Implantation,
    Journal of Applied Physics, 113, 103704 (2013).

  • R. J. Green, A. Hunt, D. A. Zatsepin, D. W. Boukhvalov, J. A. McLeod, E. Z. Kurmaev, N. A. Skorikov, N. V. Gavrilov, and A. Moewes,
    Interplay of Ballistic and Chemical Effects in the Formation of Structural Defects for Sn and Pb Implanted Silica,
    Journal of Non-Crystalline Solids, 358, 3187-3192 (2012).

  • D. A. Zatsepin, R. J. Green, A. Hunt, E. Z. Kurmaev, N. V. Gavrilov, and A. Moewes,
    Structural Ordering in a Silica Glass Matrix under Mn Ion Implantation,
    Journal of Physics: Condensed Matter, 24, 185402 (2012).

  • Hunt, A., Ching, W.-Y., Chiang, Y.-M., and Moewes, A. (2006)
    Electronic structures of LiFePO4 and FePO4 studied using resonant inelastic x-ray scattering.
    Physical Review B. 73: 205120

  • Hunt, A., Moewes, A., Ching, W.-Y., and Chiang, Y.-M. (2005)
    An indirect probe of the possible half-metallic nature of LiFePO4 using resonant inelastic X-ray scattering.
    Journal of Physics and Chemistry of Solids. 66: 2290-2294.

  • MacNaughton, J.B., Yablonskikh, M.V., Hunt, A.H., Kurmaev, E.Z., Lee, J.S., Wettig, S.D., and Moewes, A. (2006)
    Solid versus solution: Examining the electronic structure of metallic DNA with soft x-ray spectroscopy.
    Physical Review B. 74: 125101.

  • Wilks, R.G., Kurmaev, E.Z., Pivin, J.C., Hunt, A., Yablonskikh, M.V., Zatsepin, D.A., Moewes, A., Shin, S., Palade, P., and Principi, G. (2005)
    Ion irradiation induced reduction of Fe3+ to Fe2+ and Fe0 in triethoxysilane films.
    Journal of Physic-Condensed Matter. 17: 7023-7028

  • Hunt, A., Muir, D., and Moewes, A.
    Studying 4d-4f transitions in Er using resonant inelastic scattering.
    (2005) Journal of Electron Spectroscopy and Related Phenomena. 144-147: 573-576