Transport Properties of Novel Carbon Nanotubes and Nanopeapods

Transcription

1 Transport Properties of Novel Carbon Nanotubes and Nanopeapods Takashi Shimada, Yutaka Ohno, Toshiya Okazaki, Toshiki Sugai, Yousuke Nosho, Kazutomo Suenaga, Shigeru Kishimoto, Takashi Mizutani, and Hisanori Shinohara Nagoya University AIST CREST/JST July 14-18, 2003

2 Motivation Fullerenes Molecules 0 D Nanotubes Wire 1 D Peapods??? + = Thin Film Transistor MRI-contrast Reagent Transistor Infra-red Emission Field Emission How novel properties peapods show? Can peapods provides novel device? Bandgap Engineering Nano-Reactor

3 -V GS plot 1.6 C 60 -peapods T = 23 K, V DS = 20 mv Gd@C 82 -peapods / na / pa V GS / V -20 V < V GS < +20 V T. Shimada et al., APL 81, 4067 (2002)

4 T. Shimada et al., MSS11 proceedings (Physica E, accepted) T. Shimada et al., ssdm2002 extendet abstracts

5 Metallofullerene-Peapods Peapods-FET -V GS plot p-channel T = 23 K, V DS = 1 mv n-channel Ce 80 -peapods /A C 60 -peapods Ti 2 C 78 -peapods Gd@C 82 -peapods off-state ( V GS ) V / V GS -40 V < V GS < +40 V T. Shimada et al., to be submitted

6 50 Voltage width of off-state vs. Charge transfer in peapods ΔV GS, off-state -CT plot Off-state Width( V GS ) /V SWNT(HipCo,d = nm) SWNT(d = nm) C 60 -peapods C 78 -peapods Gd@C 82 -peapods Dy@C 82 -peapods DWNT(do = nm) C 90 -peapods Ti 2 C 78 -peapods Number of CT Ce C e - 3e - Ce Ce 80 -peapods Gd 92 -peapods Ce CT = 80 ΔV GS = -4 CT+25 T. Shimada et al., to be submitted

7 Nature (London) 415, 1005 (2002) (Gd ) Gd 3+ C e- C 3-82 Gd 3+ 3e-

8 Relation of ΔV and GS E g ~field field effect model~ p-channel SiO 2 V GS <0 peapod off-state ΔV GS = αe g SiO 2 peapod n-channel SiO 2 e - acc. G V GS >>0 h + acc. E C E F E V G depletion E C E F E V G peapod E C E F E V V GS

9 Relation of ΔV and GS E g ~schottkyschottky effect model~ p-channel V GS <0 E C n-channel f(e) h + E F Metal E V f(e) E F Metal e - E C V GS >0 E V

10 peapods- -V GS plot Gd@C -peapods, V = 20 mv 82 DS -T -1 plot log scale V DS = 20 mv, V GS = -10 V K 100 K 200K RT 10-9 / A / A p-channel V GS / V T T -1 / K -1 T. Shimada et al., in preparation

11 -Y 2 C 82 - peapods- -T -1 plot log scale K p-channel 30 K 23 K K -T -1 plot log scale 100 K 75 K 50 K / na T -1 /K -1 V GS = 0 V -10 V -20 V -30 V -40 V -50 V / na p-channel 0.1 RT T -1 /K -1 T T. Inoue et al., submitted T. Shimada et al., in preparation

12 -Ce V GS plot K V DS = 1 mv dip dip T, dip quenched / na K V GS / V Thermal Energy (k B T) 200 K 17.2 mev 30 K 2.58 mev T. Shimada et al., to be submitted

13 -DWNT by high temperature pulsed arc discharge- -V GS plot V DS = 1 mv 300 V DS = 1 mv, V GS = -10 V -T -1 plot log scale / A K 40K 50K 75K 100K 200K V GS / V / pa p-channel E a ~0.08eV E g ~0.17eV T -1 / K -1 T T. Sugai et al., Nano Lett. 3, 769 (2003) T. Shimada et al., in preparation

14 -SWNT by pulsed-laser laser ablation- V DS = 1 mv, V GS = -10 V -T -1 plot log scale / A p-channel Ni/Co 1.2/1.2 at.% mj/pulse Ar 300 sccm, 500 Torr T E a ~0.25eV E g ~0.5eV T -1 / K -1 T. Shimada et al., in preparation

15 -HiPco-SWNT (HCl treatment)- -T -1 plot log scale V DS = 1 mv, V GS = 0 V p-channel / A T T -1 / K -1 T. Shimada et al., in preparation

16 -T -1 plot log scale CVD-SWNT- V DS = 1 mv, V GS = -10 V / na T -1 plot linear scale p-channel / A p-channel T -1 / K T -1 / K -1 slightly depends on temperature. in preparation

17 -CVD-SWNT (Plasma Treatment)- -T -1 plot log scale V -5 V V GS = 0 V V DS = 1 mv Plasma etching / na Plasma Treatment De-scam 15 min. 1.0 p-channel T -1 / K -1 T in preparation

18 Summary (A)SWNTs by PLA (C)Peapods /A /A Scattering T -1 /K -1 T -1 /K -1 (B)SWNTs by HiPco (D)DWNTs by PA /A Scattering /A T -1 /K -1 T -1 /K -1 Peapods, HiPco, and plasma-etched CVD-CNT show diffusive transport. >>>Phonon?, Impurity?, Defect?, or <<<

19 Relation of ΔV and GS E g ~schottkyschottky effect model~ p-channel V GS <0 off-state n-channel G E C D peapod E C D peapod E C D S S S peapod E V V GS E V G V GS >0 E V

20 Voltage width of off-state vs. Fullerene size of pea in peapods ΔV GS / V C 60 -peapods C 78 -peapods Ti 2 C 78 -peapods Gd@C 82 -peapods Dy@C 82 -peapods Y 2 C 82 -peapods Ce 80 -peapods Fullerene Cage Size C 90 -peapods Gd 92 -peapods

21 Off-state vs d V DS = 1 mv, T = 23 K Diameter of CNT / nm B off-state region / V DWNT (PA) SWNT (HiPco) SWNT (PLA) C 60 -P DWNT (C2 H 2 -CVD) C 78 -P C 90 -P

22 E g vs d E gap 1 r CVD-DWNT (C 2 H 2 -zeolite) R.Saito et al., JAP 73, 494 (2001)

23 SWNT by pulsed-laser ablation and DWNT by pulsed-arc DC 10-9 V DS = 1 mv, T = 23 K 10-9 Metallic-SWNTs Metallic-DWNTs / A Semiconducting-SWNTs / A Semiconducting-DWNTs on on on p-type h + p-type h + n-type e V GS / V off V / V GS off

24 Purification and cap-opening of SWNTs H 2 O 2 (30%) reflux, ,12 hrs.

25 LT-UHV UHV-STM/STS C 60 -peapods conduction D.J.Hornbaker et al. Science 295, 828 (2002) conduction valence valence

26 Synthesis of Peapods ~Vapor Phase Reaction~ SWNTs <10-4 Torr 450~500 2 days Fullerenes 13

27 Metallofullerene M.Takata et al., Nature 377, 46 (1995)

28 HRTEM image 82 peapods Gd atom T.Shimada et al., Appl. Phys. Lett. 81, 4067 (2002)

29 Electron Energy Loss Spectroscopy (EELS) Ce 80 peapods M 5 M 4 CCD counts / a.u. CeF 3 CeO 2 Ce 80 -peapods Energy Loss / ev

30 Charge Transfer in Metallofullerene 82 ~ LUMO+1 LUMO HOMO La La@C 82 C 82 H.Shinohara, Fullerenes,Chapter 8, p.380 (2000) Figure

31 Ultara Violet Photo Electron Spectoscopy 82 Valence Band Spectra (hν= 20 ev) SOMO SOMO of 82 S.Hino et al., Chem. Phys. Lett. 281, 115 (1997)

32 Bandgap narrowing model A E C E C HOMO of Fullerens Band Formation E V E V

33 Bandgap narrowing model B E c LUMO of Fullerenes E c Band Formation E v E v

34 Synthesis of Peapods ~Vapor Phase Reaction~ SWNTs Fullerenes 2 cm Laser-Ablation method SWNT DC-Arc discharge C 60 isolated by multi-step HPLC HRTEM image of C 60 -peapods C 60 SWNT

35 CVD-CNT-FET SWNT CNT Catalyst Source Pt/Co CNT Gate Drain Pt/Co Ti/Au SiO 2 (100 nm) + p-si sub. Ti/Au 500 nm ethanol + Ar, 900, 60 min S. Maruyama et al. Chem. Phys. Lett. Source Drain Gap in Catalysts 100 μm

36 C LDA in DFT, plane wave basis set, cut off = 50 Ry M.Otani et al.

37 valence conduction C valence conduction La@C LDA in DFT, plane wave basis set, cut off = 25 Ry Y.Cho et.al, Phys.Rev.Lett.

38 Y/Ni(4.2/1.0 at.%) 600μs 50Hz 70A Ar 1atm 1000~1400

39 High temperature Pulsed Laser Ablation

40 DC Arc Discharge 500 A 25 V

41 Production of Metallofullerene DC arc discharge As-produced soot Reflux DMF, o-xylene etc.. extraction The purities of isolated fullerenes were confirmed by LD-TOF-MS system (99.9% up). EELS spectra provide a valence states of encaged metal atom in endohedral metallofullerene. Mostly, there are some electron transfer from metal to fullerene cage. Extracted fullerenes Multi-step HPLC Buckyprep column 5-PYE column Buckyclutcher column isolation Isolated fullerene Gd Ti Ti Ce Ce Gd (Ti 2 C 2 ) Ce 3+ 2@C Schematic images of charge transfer in metallofullerene..

42 Charge Transfer to CNT Gd 3+ CT C 3-82 Gd 3+ CT C 3-82 C 3-82 CT Gd 3+ Gd CT C 3-82 Gd 3+

43 82-peapod-FET P.W.Chiu et al., Appl. Phys. Lett. 79, 3845 (2001)

44 Eg1. Isolation of C 80 (II) C 86 fraction C 84 Y@C 82 1st stage 5PYE-column 312 nm UV detection 21 ml/min. toluene flow 23 ml injection C 60 C 78 C 70 Extraction; DMF C 94 C 96 5PBB column 2nd stage 5PBB-column 312 nm UV detection 21 ml/min. toluene flow 8 ml injection

45 HPLC chromatogram of extracts by o-xylene C 60 C 70 C 76 C 78 C 84 Y@C 82 (I) 5PYE 312 nm UV detection 21 ml/min. toluene flow 21 ml injection Y 5-fractions C 86 C 94 C 96