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Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Effect of the Chemical Functionalization on Charge Transport in Carbon-based.

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Presentation on theme: "Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Effect of the Chemical Functionalization on Charge Transport in Carbon-based."— Presentation transcript:

1 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Effect of the Chemical Functionalization on Charge Transport in Carbon-based materials at the Mesoscopic Scale Alejandro López Bezanilla Institut des Nanosciences et Cryogénie (INAC) CEA Grenoble, France Examiners: · Prof. Mark Casida (UJF) Président du Jury · Prof. Juan José Sáenz (UAM) Rapporteur · Prof. Alain Rochefort (EPM) Rapporteur · Dr. Xavier Blase (CNRS) · Dr. Pablo Ordejón (CIN2) Encadrants: · Dr. Stephan Roche (CEA) Encadrant · Dr. Pascale Maldivi (CEA) Co-encadrante (Grenoble) · Dr. Vincent Derycke (CEA) Co-encadrant (Saclay)

2 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 ChimTronique Transversal axes Saclay (S. Palacin) Grenoble (R. Baptist)

3 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Outline Motivations Electronic properties of CNTs and GNRs · Functionalization Decimation method · Green´s function technique Results · Functionalized nanotubes ·Functionalized nanoribbons ·Edge defects in nanoribbons

4 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 ~ 2D (sp 2 ) Graphene ~ 3D (sp 3 ) Diamond Carbon atom Valence electron orbitals: interactions between p z orbitals (bonds/bands ) Hybrid Molecular Orbitals Cohesion Electronic properties in the vicinity of E F

5 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November effective model atoms/ cellnearest neighbor orbital overlap

6 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Periodic Boundary conditions EFEF Nanotubes electronic properties Armchair Zigzag E F =0

7 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 What would it happen if we alter these properties ? Summarizing

8 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Selective electrical signals of molecular adsorption events. Protein interaction. Virus detection. Bio-, photo-sensors Zhou et al. Nano Letters 9, 1028 (2009)

9 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Left lead Right lead 300 nm Transmission after photoactive molecule functionalization. Properties of the linker. Photoactive molecules : Phtalocyanine … hvhv e-e- Bio-, photo-sensors S. Campideli et al. J. Am. Chem. Soc. 2008, 130, 11503

10 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 · MOSFETs : clean GNR-FET with ~ 3nm are necessary !!! · Ribbons down to ~ 10 nm width P. Kim et al (Columbia Univ. USA) Using top-down lithography to fabricate GNRs… E. Dujardin (CEMES, France)Ph. Avouris et al. (IBM, USA) X. Wang et al., PRL 100, (2008) X. Li et al., Science 319, 1229 (2008) W 2 nm ! Towards graphene nanoribbon transistor

11 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 A graphene-based electrochemical switch (M. Lemme & A. Geim) Functionalizing graphene 2D Graphene and Graphene ribbons Goal: how to create or enlarge energy/conduction band gaps

12 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Hybrid Carbon Based Materials Is sp 2 bonding broken/preserved?

13 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 sp 2 sp 3 Armchair nanotube axis sp 2 vs sp 3 functionalization CH 2 chemisoption Zigzag nanotube axis

14 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 sp 3 Tube axis sp 2 vs sp 3 functionalization Phenyl chemisoption

15 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Energy bands Electronic states LDoS (0.6 eV) carbene 2 phenyls carbene 2 phenyls X ΓX Γ sp 3 sp 2

16 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Efficient tool for first-principles calculations (geometrical relaxation,…) Local atomic-like orbitals basis set: · no coupling beyond a cutoff distance, · sparse Hamiltonian. No fittings, no adjustable parameters. SIESTA: an ab initio approach s-orbital p-orbital sp-hybrid orbital

17 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Size : ~ 500 atoms Building block 1.3 nm 3 nm SWCNT (10,10) phenyl groups Description of the system

18 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Order N method : only Hamiltonian - Vector products allows big systems simulations No contacts Intrinsic properties Quantum diffusion mechanism Mean free path, scattering time, mobility Kubo-Greenwood Order power N method : inversion of Hamiltonian limites size of systems simulations Accuracy Transmission and reflexion probability Localization length, conductance Landauer-Büttiker Transport formalisms

19 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Problem definition & Decimation technique Problem statement

20 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Non-interacting electrons Scattering free leads (perfect electrodes) No backscattering at lead - reservoir interface Incident electrons are in thermal equilibrium with reservoirs Problem definition Left lead Right lead Channel

21 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Problem definition Left lead Right lead channel Right leadLeft lead Nanotubes Nanoribbons

22 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Conductance from Green´s function T ( E ) = Tr [ Γ L G C Γ R G C ] (r)(a) Γ L,R = i [ Σ L,R - Σ L,R ] (r) (a) where: Fisher and Lee relation for transmission: Σ LΣ L Σ RΣ R HCHC ~ S. Fisher and P.A. Lee, Phys. Rev. Lett., 23, 6851 (1981) Datta, Electronic transport in mesoscopic system, Cambidge (1995) G C = [ E - H C - Σ L - Σ R ] - 1 ~

23 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Problem definition Left lead Right lead... Channel HCHC HRHR HLHL H = HLHL HCHC HRHR V LC V CL V RC V CR 0 0 V LC V CR HLHL HRHR HCHC N orb Semi-infinite leads + Long channel (~ orbitals) Decimation techniques

24 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Hamiltonian: Wavefunction: Energy spectrum: Eigenvalue equation: Eigenvalues: Decimation: 2-site model

25 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Decimation: 2-site model is an effective potential that corrects the non-interacting on-site energy Self-energy

26 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Decimation: 3-site model A method to reduce the dimension of the Hamiltonian basis function space

27 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Decimation: N-site model H1H1 H2H2 H3H3 H4H4 H1H1 ~ H4H4 ~ V 1,2 V 2,3 V 3,4 V 1,4 ~ V 4,1 ~

28 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Long channel decimation Left lead Right lead Building block 3 Building block 2 Pristine block Linear scaling with length: method of N order Building block 1 Building block 1

29 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Semi-infinite systems

30 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Finite system Right lead Channel Left lead H = HLHL HCHC HRHR V LC V CL V RC V CR 0 0 ~ ~ ~ N R orb N L orb N C orb Finite size Hamiltonian

31 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Green´s function technique System Green´s function: GCGC G LC G CL G RC G CR · V LC V CL V RC V CR 0 0 E-H L ~ E-H R ~ E-H C ~ = where: G CL (E-H L ) + G C V CL = 0 ~ G C V CR + G CR (E-H R ) = 0 G CL V LC + G C (E-H C ) + G CR V RC = 1 ~ ~ (1) (2) (3)

32 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Green´s function technique System Green´s function: G CL (E-H L ) + G C V CL = 0 ~ G C V CR + G CR (E-H R ) = 0 G CL V LC + G C (E-H C ) + G CR V RC = 1 ~ ~ G CL = -G C V CL g L G CR = -G C V CR g R G C = [ E-H C - Σ L - Σ R ] - 1 (1) (2) (3) where: g L = [ E- H L ] -1 g C = [ E- H C ] -1 ~ Σ LΣ L Σ RΣ R HCHC ~ Left & Right lead self-energies

33 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Functionalized CNTs Results

34 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Quasi-ballistic Diffusive Localized Transport regimes

35 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 phenyls in 300 nm Diffusive regime Metallic CNTs 200 configurations

36 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Carbenes in 1000 nm Quasi-ballistic regime Metallic CNTs 200 configurations

37 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Small radius: quasi-ballistic Large radius: diffusive !!! Semiconducting CNTs 1000 nm

38 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 sp 3 signature in metallic tubes CH 2 vs 2H Semiconducting CNTs Parallel orientation 2 Hydrogens CH 2

39 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Functionalized GNRs Results

40 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 OH/H vs phenyls sp 3 rehybridization signature T(E) is independent of functional group 4 nm wide 2 nm wide

41 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 OH/H functionalization Backscattering supression for edge functionalization Conductance dips Quantum mechanical interferences A. L. Bezanilla, F. Triozon, S.Roche Nano Letters 9, 2737 (2009 )

42 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Long nanoribbons (large gap) Mean free path 4 nm wide A. L. Bezanilla, F. Triozon, S.Roche Nano Letters 9, 2737 (2009 )

43 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Long nanoribbons (small gap) Mean free path 4 nm wide A. L. Bezanilla, F. Triozon, S.Roche Nano Letters 9, 2737 (2009 )

44 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Edge defects in GNRs Results

45 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Edge defects Experimental evidences Z. Liu, K. Suenaga, P.J.F. Harris, S. Iijima, Phys. Rev. Lett. 102, (2009) P. Koskinen, S. Malola, H. Hakkinen, Phys. Rev. Lett. 101, (2008).

46 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Benzenoid defects S.Dubois, A. L.-Bezanilla et al. Submitted to PRL

47 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Doping defects Acceptor Donor sp3-like Passivated Radical passivation Backscattering suppression

48 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Conclusions Full ab initio transport studies: SIESTA +TB_Sim sp 2 vs sp 3 functionalization Chemical modification leads to diffusive transport Benzenoid edge defects are not critical in electronic transport properties Mind the radicals! sp 3 defects induce backscattering Graphene Nanoribbons Carbon Nanotubes Decimation technique

49 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Coworkers Merci! ¡Gracias! Grazie! Tack! Merci! ¡Gracias! Grazie! Tack!

50 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Thanks for your attention

51 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009

52 Alejandro López Bezanilla – CEA-Grenoble/INAC PhD defense - November 2009 Conductance suppresion sp 3 barrier High coverage-functionalization D.C. Elias et al., Science 323, 610 (2009) Insulating regime : (towards GRAPHANE )


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