Alcohol Related Disorders Simon Pulfrey MSc, MD, CCFP December 5, 2002.
D.L. Pulfrey
description
Transcript of D.L. Pulfrey
D.L. Pulfrey
Department of Electrical and Computer EngineeringUniversity of British ColumbiaVancouver, B.C. V6T1Z4, Canada
Carbon Nanotube Field-Effect Carbon Nanotube Field-Effect Transistors:Transistors:Critique ofCritique of
High-Frequency PerformanceHigh-Frequency Performance
L.C. CastroD.L. JohnLi Chen
http://nano.ece.ubc.ca
sp2 hybridized orbital, 3e-
(-bonds)2p orbital, 1e-
(-bonds)
1s orbital, 2e-
Hybridized carbon atom graphene monolayer carbon nanotube
Carbon Nanotubes
High mobility – quasi-1D, low m*, no surface states Small SCE - coaxial geometry
L.C. Castro
Employment of Employment of metallic CNTsmetallic CNTs
T. Iwai et al., (Fujitsu), 257, IEDM, 2005
Fabricated Carbon Nanotube FETsFabricated Carbon Nanotube FETs
300 nm SB-CNFET300 nm SB-CNFETA. Le Louarn et al., APL, 90, 233108, 2007
80nm C-CNFET80nm C-CNFETA. Javey et al., Nano Lett., 5, 345, 2005
Single-tube drawbacks:
Imax ~ A
Zout ~ k
High-frequency Carbon Nanotube FETHigh-frequency Carbon Nanotube FET
A. Le Louarn et al., APL, 233108, 2007
Experimental results for fExperimental results for fTT
"Ultimate"
Carbon nanotube FETs: model Carbon nanotube FETs: model structuresstructures
C-CNFETC-CNFETD.L. Pulfrey et al., IEEE TNT, 2007
SB-CNFETSB-CNFETK. Alam et al., APL, 87, 073104, 2005
Ballistic transport Ballistic transport
dEEzQEzvEzQEzvi
dEEzQEzQzQ
EDbSbD
EDSCNT
),(),(),(),(
),(),()(
11
z sig
D
zCNT
D
G
TSD
zvdz
i
dzzQ
iQ
)(
)(
1
max,SD
max,
S
max,
max,
)ultimate""( and
)(then Q and If
),(),(
),(),()(
then
everywhere If
),(),(
),(),(),(),()(
b
G
bsig
SSD
EDS
EDS
bsig
bb
EDS
EDbSb
sig
vL
vzvQQQ
dEEzQEzQ
dEEzQEzQvzv
vv
dEEzQEzQ
dEEzQEzvEzQEzvzv
2
11
11
vvsigsig and and SDSD
SB-CNFET: summary of predictionsSB-CNFET: summary of predictions
"Ultimate"
C-CNFET: summary of predictions (July C-CNFET: summary of predictions (July 2007)2007)
C-CNFET: summary of predictions (latest)C-CNFET: summary of predictions (latest)
D.L. John et al., WOCSDICE, 2007
Energy where
most ∂Q occurs
D.L. Pulfrey et al., IEEE TNT, 2007
Regional delay timesRegional delay times
7.6 THz
Image charges in transistorsImage charges in transistors
QB QC
BJT: qb < |qe| max,max, bsigb
e
inbsig vv
QQvv
1
BJT
FET: qg |qe| max,bsig vv
+
_
+
+
_
QB+qb QC+qcqe
++
++
_
_
_
qeQS+qs QD+qd
QG+qg
FET
+
+ +++ _
__
Q(E,z) in CNFETsQ(E,z) in CNFETs
-5.5eV
SB-CNFET C-CNFET
Insignificant resonance in channel)()(
max, zQDQvv bsig
1
Comparison of vComparison of vbandband::Si NW, Si planar and Si NW, Si planar and
CNTCNT
Si NW and planar SiJ.Wang et al.,
APL, 86, 093113, 2005
(11,0) CNTTight-binding
vb,max (CNT) higher by factor of ~ 5
FET StatusW
(um)Lg
(nm)Tox (nm)
gm (mS)
Cgg (aF)
Ft (THz)
Si MOS Exptl. (IBM) 80 27 1.05 108 52 0.33
C-CN coax Theor. (UBC) 80 7 2 448 37 1.93
Si MOSFET and CNFET: Si MOSFET and CNFET: comparisoncomparison
S. Lee et al., IEDM, 241, 2005
CN oxide Gate
ConclusionsConclusions
• Multi-channel CNFETs needed for high current and for impedance matching.
• HF performance appears to be ultimately limited by vb,max.
• CNs have a vb,max advantage over Si of ~ 5 times.
• This could lead to a gm advantage (in C-CNFETs).
• Translating this advantage into superior fT and fmax will necessitate keeping
CGG low, which may be a technological issue.
• Seek applications not suited to Si.