coherent transport and resonant coupling in molecule ...asdn.net/ngc2011/presentations/reed.pdf ·...

Coherent Transport and Resonant Coupling Coherent Transport and Resonant Coupling in Molecule Transistorsin Molecule Transistors

Coherent Transport and Resonant Coupling Coherent Transport and Resonant Coupling in Molecule Transistorsin Molecule Transistors

HyunwookHyunwook SongSong1,21,2, , TakheeTakhee LeeLee11

11Gwangju Institute of Science and Technology, and Gwangju Institute of Science and Technology, and 22Yale UniversityYale UniversityHyunwookHyunwook SongSong1,21,2, , TakheeTakhee LeeLee11

11Gwangju Institute of Science and Technology, and Gwangju Institute of Science and Technology, and 22Yale UniversityYale University

Mark Reed, Yale University Mark Reed, Yale University Mark Reed, Yale University Mark Reed, Yale University

NGC2011 Moscow, Russian Federation September 14, 2011 NGC2011 Moscow, Russian Federation September 14, 2011 M. M. Reed (Yale) Reed (Yale)

Challenge:Challenge:Challenge:Challenge:gga transistor where the molecular orbital structure is modulateda transistor where the molecular orbital structure is modulated

Fabrication & design challengesFabrication & design challenges

gga transistor where the molecular orbital structure is modulateda transistor where the molecular orbital structure is modulated

Fabrication & design challengesFabrication & design challengesFabrication & design challengesFabrication & design challenges Molecular identification in the junctionMolecular identification in the junction Orbital level modulation, contact/molecular orbital coupling?Orbital level modulation, contact/molecular orbital coupling?

C h t t li ?C h t t li ?

Fabrication & design challengesFabrication & design challenges Molecular identification in the junctionMolecular identification in the junction Orbital level modulation, contact/molecular orbital coupling?Orbital level modulation, contact/molecular orbital coupling?

C h t t li ?C h t t li ?


Coherent tunneling?Coherent tunneling? Coherent tunneling?Coherent tunneling?

Spectroscopic methods (control: Spectroscopic methods (control: alkanealkane SAMs)SAMs)Spectroscopic methods (control: Spectroscopic methods (control: alkanealkane SAMs)SAMs)

L h d d i hL h d d i h lklkL h d d i hL h d d i h lklk Length dependence with Length dependence with alkanesalkanes

T independent tunnelingT independent tunneling

Length dependence with Length dependence with alkanesalkanes

T independent tunnelingT independent tunnelingp gp g

IETSIETS

p gp g

IETSIETS

10

100

I(V,T)

(80-300K) 10-2

100

10-91.0V0.9V0.8V0.7V0 6V

C8 = 0.79 Å-1

1

10

I (nA

)

C12

(80 300K)

10-6

10-4

0.4V

Jd2 (A

)

Jd (A

/cm

)10-13

10-11

0.6V0.5V

C12

-1.0 -0.5 0.0 0.5 1.0

0.1

V (V)

C12

12 14 16 18 20 22 2410-8

100.3V0.2V0.1V

Length (Å)

10-15

C12C16


W. Wang W. Wang et alet al, PRB 68, 035416 (2003); also see H.B. , PRB 68, 035416 (2003); also see H.B. AkkermanAkkerman et alet al, , NatureNature 441441, 69 (2006) , 69 (2006)

Inelastic Electron Tunneling Spectroscopy (IETS)Inelastic Electron Tunneling Spectroscopy (IETS)Tunneling electrons couple withTunneling electrons couple with vibrationalvibrational modes of moleculemodes of moleculeTunneling electrons couple with Tunneling electrons couple with vibrationalvibrational modes of moleculemodes of molecule

Elastic tunnelingElastic tunnelingeVeV < < hh

hh

II

-- hh

hhVV

I l ti t liI l ti t li

G = dI/dVG = dI/dV

ee

Inelastic tunnelingInelastic tunnelingeVeV > > hh

== ee ++ ieie

-- hh hhVV

ee ieie

-- hh

dG/dV = ddG/dV = d22I/dVI/dV22

VV

ee

ieie


hhVV

IETS on SAMsIETS on SAMs

20 0µ

0 1000 2000 3000 4000 cm-1Au-S stretching (33 meV) C-C stretching (133 meV) SAu

15.0µ

20.0µ

V2 ) CH2 wagging (158 meV)

S-C stretching (80 meV)

S

5.0µ

10.0µ

2 I/dV

2 (A/V Au

SiO-HS-H

H H

SAu

-5.0µ

0.0d2

CH2 stretching (357 meV)CH2 rocking (107 meV) CH2 scissoring (186 meV)

Si-H

Scissoring RockingC C

0.0 0.1 0.2 0.3 0.4 0.5V (V)

( )

WaggingStretching

CC2 @ T = 4 K


gg gStretching

Wang Wang et. al,et. al, NanoLettersNanoLetters 44, 643 (2004), 643 (2004)

Molecular transistorsMolecular transistorsMolecular transistorsMolecular transistors

LUMOLUMO

EEFF

HOMOHOMOSource Drain


FabricationFabricationFabricationFabrication

Drain

Source(Au)

Drain(Au)

Gate (Al2O3/Al)

•• electromigratedelectromigrated break junction technique break junction technique gg j qj qin a vacuum at 4.2 K, leads in a vacuum at 4.2 K, leads precoatedprecoated•• underlying Alunderlying Al22OO33/Al gate /Al gate •• >5K devices, ~50% open, ~30% CB & >5K devices, ~50% open, ~30% CB & other 10% asymmetric 10% operationalother 10% asymmetric 10% operationalother, ~10% asymmetric, ~10% operational,other, ~10% asymmetric, ~10% operational,~ 10% of those show significant gating~ 10% of those show significant gating Courtesy Dan Ralph (Cornell)Courtesy Dan Ralph (Cornell)


Single Molecule JunctionsSingle Molecule Junctions

ODT (n=8), BDTODT (n=8), BDT

Single Molecule JunctionsSingle Molecule Junctions

ODT (n=8), BDTODT (n=8), BDTAu

Au

10 nm

( ),( ),consistent single molecule Gconsistent single molecule G

( ),( ),consistent single molecule Gconsistent single molecule G 1 µm

Low bias (0Low bias (0--0.1V) conductance0.1V) conductanceLow bias (0Low bias (0--0.1V) conductance0.1V) conductanceNGC2011 Moscow, Russian Federation September 14, 2011 NGC2011 Moscow, Russian Federation September 14, 2011 M. M. Reed (Yale) Reed (Yale)

Single molecule junctions Single molecule junctions Single molecule junctions Single molecule junctions 0 85 Å 1

G ∝ exp(-d)g jg j


g jg j


= 0.85 Å-1

T independent tunnelingT independent tunneling T independent tunnelingT independent tunneling


Transition Voltage Spectroscopy (TVS)Transition Voltage Spectroscopy (TVS)Transition Voltage Spectroscopy (TVS)Transition Voltage Spectroscopy (TVS)

mdVI B )2(4exp

2/132

In high bias (FN tunneling),

eVVI

3exp

rewriting, dI 1)2(4 2/13

Vemd

VI B 1

3)2(4ln

2/13

2

In low bias (direct tunneling),

2/1

2)2(21lnln Bmd

VVI

J.M. Beebe J.M. Beebe et alet al, , Phys. Rev. Phys. Rev. LettLett. . 9797, 026801 (2006), 026801 (2006)

also Beebe, also Beebe, ACS ACS NanoNano 22, 827 (2008); Roth, , 827 (2008); Roth, Appl. Phys. Appl. Phys. LettLett. . 9292, 042107 (2008); Wang, , 042107 (2008); Wang, JACSJACS 131131, , 5980 (2009);5980 (2009); FrisbieFrisbie ScienceScience 320320 1482 (2008);1482 (2008); YuYu J Phys :J Phys : CondensCondens MatterMatter 2020 374114 (2008);374114 (2008);5980 (2009); 5980 (2009); FrisbieFrisbie, , ScienceScience 320320, 1482 (2008); , 1482 (2008); Yu, Yu, J. Phys.: J. Phys.: CondensCondens. Matter . Matter 2020, 374114 (2008); , 374114 (2008); Liu, Liu, ACS NanoACS Nano 22, 2315 (2008); ......, 2315 (2008); ......


TVS: Barrier (FN) Tunneling versus Coherent Transport TVS: Barrier (FN) Tunneling versus Coherent Transport TVS: Barrier (FN) Tunneling versus Coherent Transport TVS: Barrier (FN) Tunneling versus Coherent Transport

for HOMO transport

B

for HOMO transport

The coherent “resonant tail” picture surprisingly gives very similar “FNThe coherent “resonant tail” picture surprisingly gives very similar “FN--type” type” b h i (Mb h i (M A id iA id i d Md M T k dT k d Ph RPh R B 81B 81 235114 (2010) J Ch t235114 (2010) J Ch tbehavior (M. behavior (M. AraidaiAraidai and M. and M. TsukadaTsukada, , Phys Rev. Phys Rev. B 81B 81, 235114 (2010); J. Chen et , 235114 (2010); J. Chen et al, al, Phys. Rev. Phys. Rev. B 82B 82, 121412 (2010)), 121412 (2010))

Orbital energies may be different by ~10% (Orbital energies may be different by ~10% (II BaldeaBaldea ChemChem PhysPhys 377377 15 (2010))15 (2010))Orbital energies may be different by ~10% (Orbital energies may be different by ~10% (I. I. BaldeaBaldea, , ChemChem PhysPhys. . 377377, 15 (2010)), 15 (2010))


TVS: Barrier Tunneling TVS: Barrier Tunneling versus Coherent Transport versus Coherent Transport TVS: Barrier Tunneling TVS: Barrier Tunneling versus Coherent Transport versus Coherent Transport

Coherent model predicts length independent TVS Coherent model predicts length independent TVS VVtranstrans , contradicts FN model , contradicts FN model

pppp

Vtrans = 1.86 V

((HuismanHuisman et alet al, , NanoNano LettLett. . 99, 3909 (2009)), 3909 (2009))

H. Song et al. J. Phys. Chem. C 114, 20431 (2010)

-18

-16

C8C9

C10

Vtrans 1.86 V

2 0

2.4

DC8DC9

DC10DC11 DC12

g y , ( )

22

-20

ln(I/

V2 )

5

C10

C11

C121.6

2.0

Vtra

ns (V

)

DC8 DC10

-24

-22

-2 0 2-5

0

I (nA

)

V (V)

C8

8 9 10 11 121.2

N b f C b0 10 20 301/V (V-1)

Number of Carbon


Transistor transfer characteristics, ODTTransistor transfer characteristics, ODTTransistor transfer characteristics, ODTTransistor transfer characteristics, ODT

Al2O3/Al

15-8

High V Low V

a b

AuAu

S D5

10

-12

-10 VG = -3.3 V

VG = -2.8 V

VG = -2 6 VS DG

0 I (nA

)

VG = -2.8 VVG = -3.3 V

-16

-14

ln(I/

V2 ) VG = -2.6 V

VG = -2.1 V

VG = -1.6 V

-10

-5

VG = -1.1 VVG = -1.6 VVG = -2.1 VVG = -2.6 V

G

-20

-18VG = -1.1 V

VG = 0.0 V

-2 -1 0 1 2-15

V (V)

VG = 0.0 V

0 10 20 30-22

1/V (V-1)d

H. Song H. Song et alet al, , NatureNature 462462, 1039 (2009), 1039 (2009)H. Song H. Song et alet al, , NatureNature 462462, 1039 (2009), 1039 (2009)


Gate dependence of Gate dependence of VVtranstrans, ODT, ODTGate dependence of Gate dependence of VVtranstrans, ODT, ODT

1.7 1.6

D DFN

( )c d

B D BDeV EF

1.4

1.5

1.6

ans (e

V)

1.4

1.5

V (e

V) S

DeV

S

DeV

DVDV

FN

V / VA C

HOMOeVG,eff

Source DrainB

1.1

1.2

1.3eVtra

1.2

1.3

eV

SDeV

SDeV

DT

eVtrans/VG = +0.25 eV/V

dln(I/V2)/d(1/V)C A

-3.2 -2.8 -2.4 -2.0 -1.6 -1.2VG (V)

-0.8 -0.6 -0.4 -0.2eVG,eff (eV)

-0.30.25

VVtranstrans scales linearly and reversibly with scales linearly and reversibly with VVGG

Positive Positive for pfor p--type (HOMO); Negative type (HOMO); Negative for nfor n--type (LUMO)type (LUMO)

VVtrans,0trans,0 = 1.93 V for ODT, which approximates= 1.93 V for ODT, which approximates EEFFEEHOMOHOMO at zero gateat zero gate


Gate lever arm Gate lever arm –– screening is dominantscreening is dominant

S.S. S.S. DattaDatta et al, Phys Rev. B79, 205404 (2009)et al, Phys Rev. B79, 205404 (2009)S.S. S.S. DattaDatta et al, Phys Rev. B79, 205404 (2009)et al, Phys Rev. B79, 205404 (2009)NGC2011 Moscow, Russian Federation September 14, 2011 NGC2011 Moscow, Russian Federation September 14, 2011 M. M. Reed (Yale) Reed (Yale)

Transistor transfer characteristics, BDTTransistor transfer characteristics, BDTTransistor transfer characteristics, BDTTransistor transfer characteristics, BDT

cS

D

SD

S Dba

-12

-10

-8

V2 )

High V Low V

VG = -3 V 1.6

2.0

eV) eVtrans/VG

= +0.22 eV/V

) 0 310 232

4

6

VG = 2 VVG = 1 VVG = 0 VVG = -1VVG = -2 VVG = -3 V

-16

-14

12

ln(I/

V2

VG = 3 V0.8

1.2

eVtra

ns (e

0 0 0 00.81.01.21.4

eV (e

V) FN

DTS D

I(µA

) -0.310.23

-4

-2

0

VG = 3 VG

-18

0 5 10 15 20 1/V (V-1)

-3 -2 -1 0 1 2 3

0.4

VG (V)

-0.5 0.0 0.5eVG,eff (eV)G

S D

-1 0 1-6

4

V (V)

H. Song H. Song et alet al, , NatureNature 462462, 1039 (2009), 1039 (2009)H. Song H. Song et alet al, , NatureNature 462462, 1039 (2009), 1039 (2009)


Complementary transistorsComplementary transistors

SHHS

1 4

1.6 V(V

FN

-0.30.22

-0.3 0.0 0.3 0.61.2

1.4 V)

eVG,eff (eV)

DT

pp--type (HOMO) for BDT (type (HOMO) for BDT ( = +0 22) Au= +0 22) Au--SHSHpp type (HOMO) for BDT (type (HOMO) for BDT ( +0.22), Au +0.22), Au SHSH

nn--type (LUMO) for BDCN (type (LUMO) for BDCN ( = = --0.21), Au0.21), Au--CNCN

Closer to LUMO offset agrees with experiment (Closer to LUMO offset agrees with experiment (BahetiBaheti, , NanoNano LettLett. . 88, , g p (g p ( ,, ,,715 (2008)) and calculation (715 (2008)) and calculation (XueXue, , Phys. Phys. RevRev. . B 69B 69, 085403 (2004))., 085403 (2004)).


Single Molecule IETSSingle Molecule IETS

II VVAu-ODT-Au Au-BDT-Au

II--VVDCDC

dIdI//dVdV

dd22I/dVI/dV22

H. Song H. Song et alet al, , Appl. Phys. Appl. Phys. LettLett. . 9494, 103110 (2009), 103110 (2009)NGC2011 Moscow, Russian Federation September 14, 2011 NGC2011 Moscow, Russian Federation September 14, 2011 M. M. Reed (Yale) Reed (Yale)

ODTODT IETSODT IETSODT IETSODT IETS

ODT

(C

H2)

(C

-H)

CH

2)

(CH

2)C

-S)

(C-C

)

(A

u-S) (

C

(v(C v

25 50c d

15

20

25

M (m

V)

30

40

50

M (m

V)

c d

(d2 I/d

V2 )/(

dI/d

V)(C-H)

7.8 mV7.2 mV6.1 mV4.9 mV4.3 mV3 8 V 4 2 K

10 K20 K30 K40 K50 K

(C-H)

(d2 I/d

V2 )/(

dI/d

V)

5

10

15

FWH

M

10

20

30

FWH

M

0.34 0.36 0.38(

V (V)

3.8 mV

4.2 K

4.2 K

7.8 mV

0.34 0.36 0.38

(

V (V)

3 4 5 6 7 85

AC modulation (RMS value) (mV)0 10 20 30 40 50

10

Temperature (K)


IETS (VIETS (V ) ODT) ODTIETS (VIETS (V ) ODT) ODT

W b ( -1)

IETS (VIETS (VGG), ODT), ODTIETS (VIETS (VGG), ODT), ODT

1.5 0 500 1000 1500 2000 2500 3000 3500

(V-1)

Wavenumbers (cm-1)

0.40.80.37

(d2I/dV2)/(dI/dV)

(C-H)

eVG,eff = -0.75 eVeVG,eff = -0.5 eVeVG,eff = -0.25 eV(

Au-

S)

H)

a b

0.5

1.0

/dV

2 )/(dI

/dV

) (

0.2

0.3

eV (e

V)

(C-C)w(CH2)

s(CH2)

eVG,eff = 0 eV

(C

-S)

r(C

H2)

(C

-C) w(C

H2)

s(C

H2)

(C

- H

0.0 0.1 0.2 0.3 0.40.0

(d2 I/

V (V)0.00 -0.25 -0.50 -0.75

0.0

0.1

eV (eV)

(Au-S)

(C-S)r(CH2)

(C C)

S DG

V (V) eVG,eff (eV)

ODT: no electrodeODT: no electrode--orbital coupling, far from resonant systemorbital coupling, far from resonant systemODT: no electrodeODT: no electrode--orbital coupling, far from resonant systemorbital coupling, far from resonant system

BDT?BDT?BDT?BDT?


NearNear--resonant IETSresonant IETS((PerssonPersson && BaratoffBaratoff PRLPRL 5959 339 (1987) & others)339 (1987) & others)NearNear--resonant IETSresonant IETS((PerssonPersson && BaratoffBaratoff PRLPRL 5959 339 (1987) & others)339 (1987) & others)((PerssonPersson & & BaratoffBaratoff, PRL , PRL 5959, 339 (1987), & others), 339 (1987), & others)((PerssonPersson & & BaratoffBaratoff, PRL , PRL 5959, 339 (1987), & others), 339 (1987), & others)

near near eVeV = = for a molecular vibration, for a molecular vibration, the change the change in the total normalized in the total normalized tunneling conductance is (orbital energy Etunneling conductance is (orbital energy EMM , width , width , coupling , coupling E E ););near near eVeV = = for a molecular vibration, for a molecular vibration, the change the change in the total normalized in the total normalized tunneling conductance is (orbital energy Etunneling conductance is (orbital energy EMM , width , width , coupling , coupling E E ););

2 22M F

2 2 2M F M F

M F

( ) ( / 2) ( )( ) ( / 2) ( ) ( / 2)

( )1 ln

E EE eVE E E E

E E eV2 2

M F

lnπ ( ) ( / 2)

E E

Implications:Implications:Implications:Implications:

Far from resonant Far from resonant –– no change in no change in intensity, for either small intensity, for either small linewidthlinewidth or large spacingor large spacing

Far from resonant Far from resonant –– no change in no change in intensity, for either small intensity, for either small linewidthlinewidth or large spacingor large spacingg p gg p g

Near resonant Near resonant –– enhancement in enhancement in intensity, increasingly “intensity, increasingly “FanoFano--

g p gg p g

Near resonant Near resonant –– enhancement in enhancement in intensity, increasingly “intensity, increasingly “FanoFano--type” type” lineshapeslineshapestype” type” lineshapeslineshapes

MiiMii et al, Phys Rev et al, Phys Rev B 68B 68, 205406 (2003)., 205406 (2003).


BDT: resonantly enhanced IETSBDT: resonantly enhanced IETSBDT: resonantly enhanced IETSBDT: resonantly enhanced IETS

0 500 1000 1500 2000 2500

3

2

Wavenumbers (cm-1)

0.2

(8a)

a b

S) 8a)

-5.1 16.5

(d2I/dV2)/(dI/dV)

dip

peakS

(d

-1)

2

1

0 0

1

6

0.1

eV (e

V)

(C-H)

(18a)

eVG,eff = 0 eV

(Au

-S

(C

-H) (

1 8

(8a

)

peak

dippeak

dip

peak

HOMOVG,eff

SD

2I/dV2)/(dI/dV

V2 )/(

dI/d

V) (

V- 6

3

0

32

10

-0.35 -0.40 -0.45eVG,eff (eV)

eV = 0 22 eV

HOMOVG,eff

SD

5

(18a)

cPersson & Baratoff V) (V

-1)(d2 I/d

V

40

20

32

1

eVG,eff = -0.22 eV

HOMOVG,eff

SD

4

5

eVG,eff =

FitExperiment

(18a)

(%

)

model

00eVG,eff = -0.66 eV

GS D

3 0.12 0.16

d2 I/dV

2 (a.u

.)

V (V)

0 eV-0.22 eV-0.66 eV

,

0.0 0.1 0.2 0.3V (V)

-0.3 -0.4 -0.5 -0.6eVG,eff (eV)


SummarySummarySummarySummary

Molecular transistor with orbital gatingMolecular transistor with orbital gatingg gg g

Coherent transport, resonant couplingCoherent transport, resonant coupling

“n” & “p” type“n” & “p” type

Acknowledgements to J. Chen, Y. H. Jang, H. Acknowledgements to J. Chen, Y. H. Jang, H. JeongJeong, Y. Kim, I. , Y. Kim, I. KretzschmarKretzschmar, , D.R. Lombardi, C. D.R. Lombardi, C. MMüüllerller, D. , D. RoutenbergRoutenberg, , W. Wang, and C. ZhouW. Wang, and C. Zhou


coherent transport and resonant coupling in molecule ...asdn.net/ngc2011/presentations/reed.pdf ·...

Documents