1. 1 Carbon Nanotube Field-Effect Transistors Carbon Nanotube Field-Effect Transistors and their possible applications D.L. Pulfrey Department of Electrical and Computer Engineering University of British Columbia Vancouver, B.C. V6T1Z4, Canada pulfrey@ece.ubc.ca http://nano.ece.ubc.ca Day 4B, May 30, 2008, Pisa

2. 2 Single-Walled Carbon Nanotube 2p orbital, 1e - (  -bonds) Hybridized carbon atom  graphene monolayer  carbon nanotube L.C. Castro

3. 3 Chiral tube (5,2) Tube Structure (n,m): VECTOR NOTATION FOR NANOTUBES Adapted from Richard Martel Zig-zag (6,0) Armchair (3,3)

4. 4 From: Dresselhaus, Dresselhaus & Eklund. 1996 Science of Fullerenes and Carbon Nanotubes. San Diego, Academic Press. Adapted from Richard Martel. Armchair Zig-Zag Chiral CHIRAL NANOTUBES

5. 5 Carbon Nanotube Properties Graphene sheet 2D E(k //,k  ) –Quantization of transverse wavevectors k  (along tube circumference)  Nanotube 1D E(k // ) Nanotube 1D density-of-states derived from [  E(k // )/  k] -1 Get E(k // ) vs. k(k //,k  ) from Tight-Binding Approximation

6. 6 E-E F (eV) vs. k || (1/nm) (5,0) semiconducting(5,5) metallic E g /2

7. 7 low m* - maybe good for tunneling transistor to reduce sub-threshold slope low m* and long mfp - high mobility - good for I ON, g m, f T - high conductivity - good for interconnects - also, may help collection in polymer solar cells m* e = m* h - ambipolar conduction, maybe good for electroluminescence cylindrical shape - good for combating SCE Properties relevant to devices discussed at Pisa Other device possibilities: molecular size - may be useful as a molecular sensor biological compatibility - perhaps devices can be assembled via biological recognition.

8. 8 Metallic CNTs as interconnects Metallic CNTs as interconnects T. Iwai et al., (Fujitsu), 257, IEDM, 2005

9. 9 CNT-assisted organic-cell photovoltaics Keymakis, APL, 80, 112, 2002

10. 10 Is there a DIGITAL future for nanotubes?

11. 11 Tennenhouse04

12. 12 H. Dai, APS, March, 2006

13. 13 Fabricated Carbon Nanotube FETs 20nm -ve SB R.V. Seidel et al., Nano Letters, Dec. 2004 50nm MOS A. Javey et al., Stanford

14. 14 Small m*: sub-threshold slope improvement Non-thermionic process: S < 60 mV/dec !! J. Appenzeller et al., IEEE TED, 4, 481, 2005

15. 15 Carbon Nanotube FETs for HF 300 nm SB-CNFET A. Le Louarn et al., APL, 90, 233108, 2007 Single-tube drawbacks: I max ~  A Z out ~ k 

16. 16 High-frequency Carbon Nanotube FET A. Le Louarn et al., APL, 233108, 2007

17. 17 Experimental results for f T "Ultimate"

18. 18 Need full QM treatment to compute: -- Q(z) within barrier regions -- Q in evanescent states (MIGS) -- resonance, coherence -- S  D tunneling. Schrödinger-Poisson Solver D.L. John et al., Nanotech04, 3, 65, 2004.

19. 19 Schrödinger-Poisson Normalization SDCNT Unbounded plane waves

20. 20 kxkx kxkx kzkz E METAL (many modes) CNT (few modes) Doubly degenerate lowest mode MODE CONSTRICTION andTRANSMISSION T

21. 21 Quantized Conductance In the low-temperature limit: Interfacial G: even when transport is ballistic in CNT 155  S for M=2

22. 22 Carbon nanotube FETs: model structures C-CNFET D.L. Pulfrey et al., IEEE TNT, 2007 SB-CNFET SB-CNFET K. Alam et al., APL, 87, 073104, 2005

23. 23 Propagation velocity and f T

24. 24 Image charges in transistors QBQB QCQC BJT: q b < |q e | BJT FET: q g  |q e | + _ + + _ Q B +q b Q C +q c qeqe + + + + _ _ _ qeqe Q S +q s Q D +q d Q G +q g FET + ++++ _ _ _

25. 25 Comparison of v band : Si NW, Si planar and CNT Si NW and planar Si J.Wang et al., APL, 86, 093113, 2005 (11,0) CNT Tight-binding v b,max (CNT) higher by factor of ~ 5

26. 26 FETStatus W (um) Lg (nm) Tox (nm) gm (mS) Cgg (aF) Ft (THz) Si MOSExptl. (IBM)80271.05108520.33 C-CN coaxTheor. (UBC)8072448371.93 Si MOSFET and CNFET: comparison S. Lee et al., IEDM, 241, 2005 CN oxideGate

27. 27 AMBIPOLAR CONDUCTION Experimental data: M. Radosavljevic et al., arXiv: cond-mat/0305570 v1 Vds= - 0.4V Vgs= -0.15 +0.05 +0.30

28. 28 SOURCE DRAIN Ambipolar CNFET Gate-controlled light emission McGuire and Pulfrey, Nanotechnology, 17, 5805, 2006 Mobile electroluminescence and the LET

29. 29 SourceDrain Gate Analyte Spectrometer and/or Photodetector Biomolecular sensing schemes 1. Electroluminescence V GS V DS + +

30. 30 CARBON NANOTUBES: size compatibility with biomolecules, exposed surface, interactions that modify band structure, change in LDOS. CN biomolecular sensors Gruner, Anal. Bioanal. Chem., 384, 322, 2006

31. 31 Biomolecular sensing schemes 2. Conductance Star et al., Nano Lett., 3(4), 459, 2003

32. 32 Alanine-Glutamine, Glycine-Glutamine: - reduces muscle wasting in inactive patients. Arginine-Glutamine: - maintains muscle mass - boosts mucosal immunity. Sensing amino acids, dipeptides Protein building blocks Glutamine-Glutamine: - aids glutathione biosynthesis. Tyrosine-Tyrosine: - restores Phe:Tyr ratios in patients with renal disease.

33. 33 Simulation approach Molecular Dynamics GROMACS Density Functional Theory ATOMISTIX Transport Current Electroluminescence Atomic positions Electronic band structure LDOS as f(E, r, θ, z) Non-Equilibrium Green's Function ATOMISTIX

34. 34 (12,11) CNs Dipeptides: Asparagine (hydrophilic) Isoleucine (hydrophobic) MD results Abadir et al., IJHSE, accepted.

35. 35 Single-biomolecule detection Asparagine (top) and isoleucine (bottom) adsorbed on CNT between Al electrodes Abadir et al., IEEE NANO Conf.

36. 36Self-assembly of of DNA-templated CNFETs K. Keren et al., Science, 302, 1380, 2003