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GRAPHENE IN BRIEF

GRAPHENE IN BRIEF. Dat T. Do. OUTLINE. INTRODUCTION History Structure Production Properties ELECTRONIC PROPERTIE Tight binding approach QHEs (Promising) Applications. History. 1947: Graphene first used by S. Mouras Single sheets of graphite Early descriptions for CNT

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GRAPHENE IN BRIEF

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  1. GRAPHENE IN BRIEF Dat T. Do PHY 971 Presentation

  2. OUTLINE • INTRODUCTION • History • Structure • Production • Properties • ELECTRONIC PROPERTIE • Tight binding approach • QHEs • (Promising)Applications PHY 971 Presentation

  3. History • 1947: Graphene first used by S. Mouras • Single sheets of graphite • Early descriptions for CNT • Epitaxial graphene • Polycyclic aromatic hydrocarbons • None of above is isolated PHY 971 Presentation

  4. Structure 12 Pentagons Bucky Ball Rolling Nanotube d = 0.142 nm Stacking Graphite • Predicted not to exist • by Landau and Peierls (1935, 1937)??? PHY 971 Presentation

  5. Growing methods • Drawing: Andre Geim el at, 2004 • Epitaxial grow: Peter W. Sutter at Brookhaven National Laboratory, 2008 • Silicon Carbide Reduction • Hydrazine Reduction: Yang Yang et al, UCLA, 2008 • Chemical vapor deposition:Kim et al, 2009 • Cutting Carbon nanotube:2009 February 2009 PHY 971 Presentation

  6. Unique Properties • Strongest bond • High thermal conductivity: 4.8 x 103. • Absorbing 2.3% of white light • Small spin-orbit coupling • Spin-polarized edge: Nano-trip zig-zag. • Unique Electronic properties PHY 971 Presentation

  7. Tight binding approach LCAO + Secular eqn. PHY 971 Presentation

  8. Graphene π – Bandnearest neighbor PHY 971 Presentation

  9. Band Structure • Semi-metal (zerogap) • m* = 0 near point K • Dirac fermion Dirac Point vf ~ 106 m/s Novoselov et al 2005; Zhang et al 2005 PHY 971 Presentation

  10. Ambipolar electric field effect • μ : 15000 cm2V-1s-1. Weakly Temp-Dependent • Lowest resistivity substance ever. • Minimum conductivity: 4e2/h PHY 971 Presentation

  11. Quantum Hall Effect σxxy = ±4e2/h (N + ½) PHY 971 Presentation

  12. Promising Applications • Single molecule Gas detection • Electronic device, integrating circuit: silicon replacement • Transparent conducting electrode • Psuedo relativistic theory. PHY 971 Presentation

  13. “… graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.” (A. K. Geim and K. S. Novoselov) PHY 971 Presentation

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