SWAN sourcedrain Moores Law No exponential is forever! But can we delay forever?
-
Upload
denisse-totty -
Category
Documents
-
view
220 -
download
0
Transcript of SWAN sourcedrain Moores Law No exponential is forever! But can we delay forever?
SWANSWAN
source drain
Moore’s Law
No exponential is forever!
But can we delay “forever”?
SWANSWANCavin, Hutchby, Zhirnov, Bourianoff
SWAN
SWAN
Cavin, Hutchby, Zhirnov, Bourianoff
SWAN
A=0
Precession of phase
+ C
x
B=0
A=0, B=0 C=0
A=0, B=1 C=1
A=1, B=0 C=1
A=1, B=1 C=0
A
B
C
Out
A
B
C
Out
DMS: A&M, Maryland, UTMQCA:ND
Phasetronics: UT Path Integral Monte Carlo: ASU, UT
Pseudospintronics on Graphene: UT, UTD, Maryland
Future of Microelectronics: The beginning of the end or the end of the beginning?
Sanjay Banerjee, Univ. of Texas
Task 5: Nanoscale CharacterizationUTD
Task 4: Nano plasmonic interconnectsRice
Task 3: Nanoscale Thermal ManagementUIUC, NCSU
Γ ΓK MPho
no
n F
req
uen
cy (
cm-1)
Graphene Monolayer
Task 2:Spintronics in DMSTask 1: Logic Devices with Alternate State Variables
SWAN
South West Academy of Nanoelectronics
TI, Intel, IBM, Micron, AMD, Freescale,
NIST
Texas ETF
SWANSWAN
DNA~2-1/2 nm diameter
Things NaturalThings Natural Things ManmadeThings Manmade
Fly ash~ 10-20m
Atoms of siliconspacing ~tenths of nm
Head of a pin1-2 mm
Quantum corral of 48 iron atoms on copper surfacepositioned one at a time with an STM tip
Corral diameter 14 nm
Human hair~ 60-120m wide
Red blood cellswith white cell
~ 2-5 m
Ant~ 5 mm
Dust mite
200 m
ATP synthase
~10 nm diameterNanotube electrode
Carbon nanotube~1.3 nm diameter
O O
O
OO
O OO O OO OO
O
S
O
S
O
S
O
S
O
S
O
S
O
S
O
S
PO
O
The Challenge
Fabricate and combine nanoscale building blocks to make useful devices, e.g., a photosynthetic reaction center with integral semiconductor storage.
Mic
row
orld
0.1 nm
1 nanometer (nm)
0.01 m10 nm
0.1 m100 nm
1 micrometer (m)
0.01 mm10 m
0.1 mm100 m
1 millimeter (mm)
1 cm10 mm
10-2 m
10-3 m
10-4 m
10-5 m
10-6 m
10-7 m
10-8 m
10-9 m
10-10 m
Visib
le
Na
no
wo
rld
1,000 nanometers = In
frare
dUl
travio
let
Micr
owav
eSo
ft x-
ray
1,000,000 nanometers =
Zone plate x-ray “lens”Outer ring spacing ~35 nm
Office of Basic Energy SciencesOffice of Science, U.S. DOE
Version 10-07-03, pmd
The Scale of Things – Nanometers and MoreThe Scale of Things – Nanometers and More
MicroElectroMechanical (MEMS) devices10 -100 m wide
Red blood cellsPollen grain
Carbon buckyball
~1 nm diameter
Self-assembled,Nature-inspired structureMany 10s of nm
More is different!
Smaller is different!
SWANSWAN
SWAN
Subthreshold leakage is diffusion
current from S to D (as in BJT)
S= ln10 kT/q (1 + Cd/Cox)
SWANSWAN
)(1
1][ TG
c
cTODSAT VV
r
rWvCI −⎟⎟
⎠
⎞⎜⎜⎝
⎛
+−
=
( ) 20
1
2D X G T D D
WI C V V V V
Lμ
⎡ ⎤= − −⎢ ⎥⎣ ⎦
( )2
0
1
2DSAT X G T
WI C V V
Lμ
⎡ ⎤= −⎢ ⎥⎣ ⎦
( ) satvD OX G TI WC V V≈ −
SWANSWAN
Bandstructure effective mass, m*, is inversely related to curvature of bands, and depends on crystal orientation and strain.Density of states m* is related to geometric mean of bandstructure m*.
Conductivity m* is harmonic mean of bandstructure m*.
m* =31
m1* +
1m2
* +1
m3*
⎛
⎝⎜
⎞
⎠⎟
−1
=e τ
m *
m* = m1*m2
*m3*( )
13
( ) ( )212
3
2
*
4 cde
c EEh
mEg −⎟⎟
⎠
⎞⎜⎜⎝
⎛= π
⎟⎟⎠
⎞⎜⎜⎝
⎛=
2
2
2*
dkEd
mh
Effective2 2 2
* *( ) ( ) ( )
2 2
p kE k V r V r
m m= + = +
h
SWAN
• Gapless, unless GNR• Electric field induced gap in bi-layer• Linear E(k) at K point; Dirac massless fermions
Min, Sahu, Banerjee, MacDonald, PRB (2007)
Uext=0 , Egap=0
Γ K
K′M
k space
Graphene Bandstructure Graphene Bandstructure
SWANSWAN
300
200
100
0Tunneling Conductance (10
-9Ω
-1)
-5 0 5 ( )Interlayer Voltage mV0
dIT/d
V
0
V
I. Spielman et al., Phys. Rev. Lett. 84, 5808 (2000)
Charge-neutral superfluid: Bose-Einstein condensate of excitons! Electron-hole pairing enhanced interlayer conductance with NDR
Pseudospintronics in Bilayers at low T, high B Pseudospintronics in Bilayers at low T, high B
SWANSWAN
Atomic Levels:
Electrons in Magnetic
Field:
Electrons in Atomic Orbitals:
E0
E2
E1
E3B ħc
ħc
ħc
Electrons in a Magnetic Field: Landau Levels
(Landau levels) En = (n + 1/2) hc
c =eB
me
Macroscopic degeneracy: eB/h = 2.421010cm-2 T
SWANSWAN
Re
sist
ance
Magnetic Field
hc B
B BI
Vxy
• •
Filling factor = 2 = 1
(von Klitzing, 1980)
Quantum Hall Effect
SWAN
electron precession in magnetic field
Spin Precession Precession Starts on application of Magnetic Field B
Electron Spin
SPIN
MAGNETIC MOMENT
MAGNETIC FIELD
μ X H
mħ
11 12
21 22
H H
H H
⎛ ⎞⎜ ⎟⎝ ⎠
( )
( )z x y
x y z
B B iB
B iB B
− − −⎛ ⎞⎜ ⎟+ +⎝ ⎠
Polar angles (θ, φ)
H = - μ. B =
SWANSWAN
Quantum 2-Level Systems
cos(/2) +sin(/2) eiφ
cos(/2) +sin(/2) eiφ A B
cos(/2) +sin(/2) eiφ
top layer:
bottom layer: ↑
↓
SWAN
Pseudo-spintronic devices• Device consisting of two electron and/or hole layers in close proximity
• Inter-layer electron-electron interaction strong “layer” (pseudo-spin) degree of freedom uncertain
• Charge transport intimately determined by the dynamics of the pseudo-spin degree of freedom
zizj
wi wj
• ∏ ∏∏< <
= −−−Ψ=Ψji ji
jiji
jji wzwiwzz
,1111 )()()(~ν
= 1/2
= 1/2d ~ lB
SWAN
Intra-layer vs Inter-layer interaction
eB
hlB =
d
Einter=e2
d
Eintra=e2
lB
Eintra
Einter
d
lB=
Expect exciting physics when d/lb 1
B
B
A
eBl
o
B
256==
h
SWANQuantum Hall Effect-Counterflow transport in GaAs-AlGaAs
Vanishing counterflow longitudinal and Hall resistivities at =1 QHS Charge-neutral superfluid: Bose-Einstein condensate of excitons! Electron-hole pairing enhanced interlayer conductance
0.0 0.5 1.0 1.5 2.0 2.50
10
20
30
40
50
Vxy
I
I
Vxx
ρxx(kΩ/o)
ρxy(kΩ)
B(T)
pT=p
B=2.75?1010 cm-2
d/lB=1.3
T=30mK
0
10
20
30
40
50
4 2 ν=1
+
-
I
I
Vxx
Vxy
E. Tutuc et al., Phys. Rev. Lett. 93, 036802 (2004).
SWANSWANGraphene bilayer with excitons formed by MOS gate
Prediction of above room temperature existence of electron-hole condensate
holes in valence band
electrons in conduction band
•Room-Temperature Superfluidity in Graphene Bilayers?, • Min, Bistritzer, Su, MacDonald •How to make a bilayer exciton condensate flow,•Su, MacDonald
+
SWANBi-layer pseudoSpin Field Effect Transistor (BiSFET)
Banerjee, Register, Tutuc and Macdonald
“Bilayer pseudoSpin Field Effect Transistor (BiSFET): a proposed new logic device” S.K. Banerjee, L.F. Register, E.Tutuc, D.Reddy and A. Macdonald., IEEE EDL, accepted (2008); also patent disclosure
SWAN
0 5 10 15 20 250
1
2
VG'
ViL (mV)
I (A)
VG
BisFET simulated output characteristics as a function of interlayer bias and gate bias. VG’ puts the device in an unbalanced state, leading to lower currents
44
max
max
)/||1exp(
/)(1)(
−
⎥⎥
⎦
⎤
⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛
−−−
+−=VVV
VVVVVGI
np
npnpo max max, exp( 10 | | /( ))oV V p n n p= − Δ −Δ +
Layer1:Electrons [n]
Inter layer bias
Many body tunneling
Layer2:Holes [p]
Bose condensation of excitons [e-h pairs]
Tc = 0.1Ef/kB; Tc = 300K implies n=p=4.9x1012 cm-2 which is possible by gating
Inter layer current
1~
F
sJ
ok
ρλ⎛ ⎞⎜ ⎟Δ⎝ ⎠
j
seGVI
λρ
h== maxmax π h
FF
F Ekk
h
eG == ;4
2
SWANInverter layout with complementary BisFETs and SPICE simulation
0
25
0
25
0 50 100 150 2000
25
Output (mV)
Input (mV)
Vsupply
(mV)
00 0
1
1 1
10 01
Time (ps)
1.0 nm EOT, gate L=10 nm, corresponding to the Josephson length, and W=20 nm. Clock frequency= 100 GHz and Vclock,peak 25 mV with 2.5 ps rise time. Input and output signals were subject to a fan-in and fan-out of 4 inverters. Current MOSFETs consume ~100 aJ per switching and 2020 “end of the roadmap CMOS will consume ~5 aJ [www.itrs.net]. Energy consumed per switching operation per BiSFET= 0.008 aJ! (2X Landauer limit)
SWAN
pGpC
nGnC
A
( )tVclock
B
C
mV 52−+
−
pGpC
nGnC
8=LW
2=LW2=
LW
pGpC
nGnC
+
−
switchV
BACmVVIf
BACmVVIf
switch
switch
•=−=
+==
,25
,0
• Clock: – Vlow = 0mV ; Vhigh= 25mV– Rise time= 2.5 ps– Fall time = 2.5 ps– Pulse width = 2.5ps– Pulse period =10 ps– Frequency of cock = 100 GHz– Delay between clock and input signal is 2.5 ps
• Maximum number of inverters the OR gate can drive: 6• Energy per operation:
– For OR GATE (load = 4 inverters) total energy for 4 operations: 133.7 x 1E-21 J
– Average Energy per operation 33.4 x 1E-21 J– For NAND GATE(load = 4 inverters) total energy for 4
operations: 121.81x1E-21 J– Average Energy per operation 30.45 x 1E-21 J
OR and NAND Gate
SWAN
0
25
0
25
0
25
0 10 20 30 400
25
Vclock
(mV)
A (mV) 0 0 1 1
B (mV) 00 1 1
Time (ps)
C (mV) 0
mVVswitch 25−=
BAC •=
NAND gate operation
SWANSWAN
The Collective FET vision
kBT/nq ~ about 25mV/n
SWAN
Graphene MOSFET Fabrication and Modeling
Carrier density in the channel induced by VTGCarrier density in the channel induced by VTG
Quantum Capacitance in GrapheneQuantum Capacitance in Graphene
VTG and carrier density, n, relationVTG and carrier density, n, relation
SWANR vs (VTG-VDirac) with model: 15nm Al2O3 Top-gated FET
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0500
1000
1500
2000
VBG
= +40 VV
BG= +10 V
VBG
= 0 VV
BG= - 10 V
R R R R R R R R R Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1 Fit Curve 1
Resistance
(Ω)
VTG-V
DIRAC(V)
Parameters Extracted Values
n0 (cm-2) 3.19– 4.28 x 1011
Mobility (cm2/Vs)
4,434- 6,190
Rcontact (ohm) 552 - 1579
Thinner dielectric layer
lower remote charge impurities in oxide
Lower initial carriers less carrier scattering
Higher mobility
Mobility independent of T
Thinner dielectric layer
lower remote charge impurities in oxide
Lower initial carriers less carrier scattering
Higher mobility
Mobility independent of T
60 80 100 120 140 160 180 200 220 240 260 280 300 3200
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Mobility (cm
2/Vs)
Temperature (K)
God made solids; surfaces on the other hand are the work of the devil. (Pauli)
SWAN All Graphene Electronics
DARPA Carbon Era Rf Applications (CERA) program with IBM
LNA, interconnects, …
SWAN
Tight Binding Model of Graphene
Nearest neighbor (NN) tight binding Hamiltonian:
, for NN, 0 otherwise. self-consistent potential.
ij ij i ijH tN qφδ= −1ijN =
iφPerfect armchair graphene ribbon showing equal no. of atoms in successive slices.
Corresponding band structures:
No. of atoms in the slice = 7, 8 and 9
SWAN
T(E) vs. E [different roughness (identical Wch)]
T(E) vs. E for a 7.63 nm wide graphene channel having different roughness. r = 0.5 » random, r = 1 » perfect.
SWAN
A=0
Precession of phase+ C
Phasetronics: AB device with Rashba Effect Register, Banerjee
Phasetronics: AB device with Rashba Effect Register, Banerjee
x
B=0
EX OR Gate
A=0, B=0 C=0
A=0, B=1 C=1
A=1, B=0 C=1
A=1, B=1 C=0
State 0: Electron transmission is suppressed State 1: Electron transmission is permitted
SWANResonant Injection Enhanced Field-Effect Transistor
Patent disclosure, Register, Banerjee
SWAN
ON/OFF states of RIEFET
ON state (Vg=150mV in following examples):
The multiple quantum-wells below the gate serve as a nearly transparent high-order band pass filter for electrons;
OFF state (Vg=0mV):
The gate not only raises the channel potential directly beneath the gate relative to the source, but destroys the inter-well resonances and reduce access to the channel even for electrons with sufficient thermal energy.
Energy levels of quantum states
Energy levels of quantum states
Aligned
Misaligned
Transport direction
Transport direction
Top gate
Top gate
SWANSpintronics- Datta-Das Transistor
Electrons quantum mechanically can be viewed as a spinning top which can point “up” or “down”!
SWAN
1 10 0
A
B
C
Out
-11 10
Binary wire
InverterMajority gate
MA
B
C
Programmable 2-input AND or OR gate.
Nanomagnet-Based Logic- MQCAWolfgang Porod and Gary Bernstein, Univ. Notre Dame
SWAN
ITRS, 2005
SWANWhat is needed in the new switch?
Speed = CV/I
Active Power = CV2f
Stand-by Power = Sub-VT, gate leakage
Desirable Attributes
•Energy efficiency
•Speed (performance, noise)
•Room T operation (non-equilibrium devices?)
•Size (device/ wafer): capacitance, fan-out
•Gain; uni-directional signal flow (I/O isolation)
•Reliability, manufacturability, cost
•CMOS compatibility (process, topology)
CMOS CMOS caca 2020 2020Energy ~ 10 aJ/op; power~ 10Energy ~ 10 aJ/op; power~ 1077 W/cm W/cm22
Speed ~ 0.1 ps/op (10 THz fSpeed ~ 0.1 ps/op (10 THz fTT; 100 GHz circuit); 100 GHz circuit)Size ~ LSize ~ Lgg 5 nm; cell ~ 100 nm, I 5 nm; cell ~ 100 nm, IDNDN~ 3 mA/~ 3 mA/µµmmDensity ~ 10Density ~ 101010 cm cm-2-2; BIT ~100 GBit/ns/cm; BIT ~100 GBit/ns/cm22
Cost ~ 10Cost ~ 10-12-12 $/gate $/gate
0.01 aJ/op
100GHz
Yes
10 nm, FO=4
???
Yes
???