Field Effect Transistor Behaviour in Single Wall Carbon Nanotubes and Peapods

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