1 / 11

What is graphene?

What is graphene?. In late 2004, graphene was discovered by Andre Geim and Kostya Novoselov (Univ. of Manchester). - 2010 Nobel Prize in Physics . Q1. How thick is it? a million times thinner than paper ( The interlayer spacing : 0.33~0.36 nm) Q2. How strong is it?

kayo
Télécharger la présentation

What is graphene?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. What is graphene? In late 2004, graphene was discovered by Andre Geim and KostyaNovoselov (Univ. of Manchester). - 2010 Nobel Prize in Physics • Q1. How thick is it? • a million times thinner than paper • (The interlayer spacing : 0.33~0.36 nm) • Q2. How strong is it? • stronger than diamond • (Maximum Young's modulus : ~1.3 TPa) • Q3. How conductive is it? • better than copper • (The resistivity : 10−6Ω·cm) • (Mobility: 200,000 cm2 V-1 s-1) But, weak bonding between layers Seperated by mechanical exfoliation of 3D graphite crystals.

  2. Molecular structure of graphene 2D graphene sheet Carbon Electrons move freely across the plane through delocalized pi-orbitals CNT bucky ball 3D graphite

  3. Electronic structure of graphene Effective mass (related with 2nd derivative of E(k) )  Massless Graphene charged particle is massless Dirac fermion.  Zero gap semiconductor orSemi-metal Pz anti bonding Conduction band Ef K Fermi energy K’ Pz bonding Valence band K 2DEG K’

  4. Electrical properties of graphene High electron mobilityat room temperature: Electronic device. Si Transistor, HEMT devices are using 2D electron or hole. μ (mobility) = vavg/ E(velocity/electric field) Jdrift ~ ρx vavg

  5. Optical properties of graphene Optical transmittance control: transparent electrode Reduction of single layer: 2.3% F. Bonaccorso et al. Nat. Photon.4, 611 (2010)

  6. Mechanical properties of graphene Mechanical strength for flexible and stretchable devices Young’s modulus =tensile stress/tensile strain Diamond ~ 1200 GPa Force-displacement measurement C. Lee et al. Science321, 385 (2008)

  7. Graphene growth by chemical vapor deposition SiC sublimation Metal catalysis CVD Ni: non uniform multi Cu: uniform single  Cu: layer by layer growth Current Status Solid Carbon : Low temp. Nat.mat.2009.203. Ar1atm,1450~1650°C Terrace size increase. Nat.2010.549. ACS nano,2011 High temperature growth :1200~1500°C Non-uniform growth in Step edge and terrace. High cost SiC wafer : SiC growth on Si No transfer required Low temperature growth :below 1000°C Unform growth : Capet like (Large area) Si CMOS compatible process. “Transfer required” Pros& Cons

  8. Large area graphene K. S. Kim et al. Nature457, 706 (2009) S. Bae et al. Nat. Nano.5, 574 (2010)

  9. PSCs with graphene anodes a b PEDOT :PSS PTB7 -F40 TiOx Al 3.3 4.3 4.3 4.3 5.0 5.1 5.4 6.0 GR/PEDOT: PSS (DT) PC71BM 8.0 eV

  10. PLEDs with graphene anodes Al Ca PEDOT :PSS SY 2.4 2.9 4.3 4.8 eV 5.1 GR/PEDOT: PSS (DT) 5.4

  11. PLEDs with graphene or ITO anodes 2 cm

More Related