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Field Effect Transistor Behavior in Carbon Nanotubes

Explore the behavior of carbon nanotubes and peapods in field effect transistors, focusing on contact importance, Coulomb blockade, odd-even effects, and magnetic contacts. Learn about hybrids with GaAs, periodic modulation, and more at this 2004 workshop.

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Field Effect Transistor Behavior in Carbon Nanotubes

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  1. Field Effect Transistor Behaviour in Single Wall Carbon Nanotubes and Peapods Isaac Newton Institute Workshop, Cambridge 27-30 September 2004 Poul Erik Lindelof Niels Bohr Institute, Nano-Science Center, University of Copenhagen Niels Bohr Institute

  2. Field Effect Transistor Behaviour in Single Wall Carbon Nanotubes and PeapodsPoul Erik LindelofNiels Bohr Institute, Nano-Science Center, University of Copenhagen Henrik Ingerslev Jørgensen, PhD student Jonas Rahlf Hauptmann, PhD-student Thomas Sand Jespersen, PhD-student Kasper Grove-Rasmussen, Ph.D.-student (p.t. visiting NTT BRL, Japan) Ane Jensen, Dr Jesper Nygård, Dr & collaboration with Andrei Khlobystov, Oxford University Niels Bohr Institute

  3. Field Effect Transistor Behaviour in Single Wall Carbon Nanotubes and Peapods Outline of talk: Importance of contacts, Coulomb blockade, odd-even effects due to spin Zeeman splitting, ESR? Kondo effect Hybrids with GaAs Magnetic contacts Peapods, Periodic modulation Summary Niels Bohr Institute

  4. 3 carbon nanotubes (10,10) (15,0) (12,8) Niels Bohr Institute

  5. TEM of carbon nanotube robe A nanotube (or two?) TEM picture 20 nm Niels Bohr Institute

  6. Assignment by Raman spectra Thomas Sand Jespersen, MSc thesis Niels Bohr Institute

  7. although carbon atoms only! Contact configuration 2-point Electrical Resistance drain • Au/Ti contacts • Carbon nanotube • Silicondioxide (300 nm) • Highly doped silicon source gate Niels Bohr Institute

  8. Contacting a SWCNT 10µm 50µm Niels Bohr Institute

  9. SWCNT, metals or semiconductors Niels Bohr Institute

  10. 3 examples of Contact resistances G300K = 0.3 e2/h G300K = 1.8 e2/h G300K = 3 e2/h T = 1K Theoretical maximum Gmax = 4 e2/h T = 100mK Niels Bohr Institute

  11. Metallic SWCNT, Temperature Dependence P.E. Lindelof, et al., Physica Scripta T02, 22 (2002) Niels Bohr Institute

  12. Odd-Even Additional energies D.H. Cobden and J. Nygård Phys,Rev,Lett. 89, 046803 (2002) Niels Bohr Institute

  13. Bias Spectroscopy, Zeeman splitting 0T a b 6T P.E. Lindelof , et al., Physica Scripta T02, 22 (2002) Niels Bohr Institute

  14. Wolfgang Pauli and Niels Bohr 1951, looking at a spinning object! Niels Bohr Institute

  15. E O E O E O E Q eV D P Q P Kondo bias spectroscopy J. Nygård et al., Nature 408,342 (2000) Niels Bohr Institute

  16. c a b G0 (e2/h) TK (K) a 1.72 1.6 b1.77 0.9 Kondo temperature J. Nygård et al., Nature 408, 342 (2000) Niels Bohr Institute

  17. Carbon nanotube inside a MBE GaAlAs single crystall = + A. Jensen, J.Hauptmann, J, Nygård, J. Sadowski, P.E. Lindelof, Nano Letters (2004) Niels Bohr Institute

  18. MBE chamber Device fabrication MBE grown substrate: - n-doped GaAs - insulating superlattice barrier - amorphous As cap (protection) Dispersion of single-wall nanotubes from suspension, ambient conditions Niels Bohr Institute

  19. MBE chamber Device fabrication Epitaxal overgrowth with Ga0.95Mn0.05As by MBE at 250 C Result: nanotubes incorporated in GaAs sandwich Reloaded in the MBE chamber Desorption of As cap at 400 C, leaving the nanotubes on the clean GaAs crystal surface Niels Bohr Institute

  20. Mesa, Trench etch, SWCNTs Trench and SWCNT Niels Bohr Institute

  21. Device architecture Au/Zn a) b) (Ga,Mn)As 7 SWNT 5 4 6 Cr/Au 3 x100 2 AlAs 1 GaAs Niels Bohr Institute

  22. Configurations in various magnetic fields Niels Bohr Institute

  23. GaAs GaAs AFM scan of SWCNT between MBE grown GaAs electrodes Single wall carbon nanotube The trench is 0.5 µm wide Niels Bohr Institute

  24. G(Vg,B) for GaMnAs-SWCNT-GaMnAs Niels Bohr Institute

  25. G(Vsd,B,T) for GaMnAs-SWCNT-GaMnAs Niels Bohr Institute

  26. Magnetoresistance of GaMnAs-SWCNT-Au Niels Bohr Institute

  27. Juliere’s model n(1,+) n(1,-) n(2,+) n(2,-) G(++)~n(1,+)n(2,+)+n(1,-)n(2,-) G(+ -)~n(1,+)n(2,-)+n(1,-)n(2,+) P(1)=[n(1,+)-n(1,-)]/[n(1,+)+n(1,-)] DG/G=[G(++)-G(+ -)]/G(++) =2P(1)P(2)/[1+P(1)P(2)] >0 Negative magnetoresistance Niels Bohr Institute

  28. Tunnelling into two domains (Streda, unpublished) T(1,-) Tt T(1,+) T(2,-)= T(2,-) T(1,+)=pT1, T(1,-)=(1-p)T1, T(2,+)=T(2,-)=T2 G(p=1)=G(+)+G(-)=T1TtT2/[Tt(T1+T2)+2T1T2] G(p=1)-G(p=½)= -G(p=1)[T1/T2 + 2T1/Tt] magnetoresistance>0 Niels Bohr Institute

  29. C-60@SWCNT Peapod K. Haldrup, A.N. Khlobystov et al. Niels Bohr Institute

  30. Raman spectra a) SWCNT b) SWCNT - through treatment c) C-60@SWCNT Peapod - through treatment Niels Bohr Institute

  31. Peapod Conductance vs. Vg Niels Bohr Institute

  32. G(290) vs. power law exponent.C-60@SWCNT (O) & SWCNT (l) Haldrup, Khlobystov et al., To be published Niels Bohr Institute

  33. Nanometer periodic modulation of potential along SWCNT Thomas Sand Jespersen, Poul Erik Lindelof, unpublished Niels Bohr Institute

  34. MBE growth of SL with guiding structures. Cleaved Edge Overgrowth Niels Bohr Institute

  35. AFM picture of cleaved and etched surface Niels Bohr Institute

  36. AFM study of 30 nm period superlattice on the cleaved edge Niels Bohr Institute

  37. Carbon nanotube decoration of CEO SL surface Niels Bohr Institute

  38. SWCNT superlattice Raman spectrum.No data for the combination yet. Niels Bohr Institute

  39. Summary The contact resistance to metallic carbon nanotubes, Temperature dependence of electrical conductance Odd-even Coulomb blockade conductance peaks Zeeman splitting (g=2) Spin ½ co-tunneling (Kondo effect) GaAs-CNT hybrids, magnetic contacts Peapods, CEO periodic modulation Niels Bohr Institute

  40. Movie of ”spinning object” Niels Bohr Institute

  41. The ”spinning object” in action Niels Bohr Institute

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