vii
TABLE OF CONTENTS
CHAPTER
TITLE
DECLARATION
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT
ABSTRAK
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF ABBREVIATIONS
LIST OF SYMBOLS
LIST OF APPENDICES
1
INTRODUCTION
1.1
Research Background
1.2
Production
1.3
Objective
1.4
Problem Statement
1.5
Scope of the Study
1.6
Summary
1.7
Organization of project
2
LITERATURE REVIEW
2.1
Graphene Nanoribbon
2.1.1
Structure of Graphene Nanoribbon
2.1.2
Properties of Graphene Nanoribbon
2.1.2.1 Electron Transport in Armchair
GNR
2.1.2.2 Electron Transport in Zigzag GNR
2.1.3
Growth of Graphene Nanoribbon
PAGE
ii
iii
iv
v
vi
vii
x
xi
xiii
xv
xviii
1
1
4
5
5
6
6
7
8
8
8
10
12
15
16
viii
2.2
2.3
2.4
2.5
2.6
2.1.3.1 Chemical Method
2.1.3.2 Unzipping Carbon Nanotubes
2.1.3.3 Lithography
Graphene Nanoribbon Field Effect Transistor
2.2.1
Device Structure of GNRFET Nanoribbon
Field Effect Transistor
2.2.1.1 Single Gate GNRFET
2.2.1.2 Wrapped Gate GNRFET
2.2.1.3 Double Gate GNRFET
2.2.2
Operation of GNRFET
2.2.2.1 Schottky-Barrier GNRFET
2.2.2.2 MOSFET-like GNRFET
Type Complementary metal oxide semiconductor base
on metal
2.3.1
Silicon Complementary metal oxide semiconductor (SiCMOS)
2.3.2
Carbon nanotube completely metal oxide
semiconductor (CNTCMOS)
2.3.3
Graphene nanoribbon completely metal
oxide semiconductor (GNR CMOS)
Inverter
Applications of Monolayer Graphene
2.5.1
2D graphene FETs
2.5.2
Epitaxial graphene RF FETs on SiC for
analog applications
2.5.3
Wafer-scale 2D graphene FETs
2.5.4
Long channel graphene FET model
Summary
17
19
20
24
24
26
26
28
29
29
31
32
32
35
38
39
40
41
43
44
46
46
3
RESEARCH METHODOLOGY
3.1
Importance of GNRCMOS
3.2
Research Methodology Flowchart
3.3
MODELLING
3.4
MATLAB Model and T-spice
3.5
Analysis of GNRCMOS Gate
49
50
53
53
54
55
4
CONCLUSION
4.1
Introduction
56
56
ix
4.2
4.3
4.4
4.5
5
Comparison between GNR and CNT
Modelling
Simulation results
4.4.1
I-V characteristics
4.4.2
Voltage Transfer Characteristics (VTC)
4.4.3
Comparison between conventional CMOS
(SiCMOS) and GNRCMOS
4.4.4
Gain
Summary
CONCLUSION AND FUTURE WORK
5.1
CONCLUSION
5.2
Recommendations for Future Work
56
57
59
60
64
66
67
68
69
69
70
REFERENCES
72
Appendix A
77
x
LIST OF TABLES
TABLE NO.
4.1
4.2
4.3
TITLE
Relationship between VGS and IDS in SiNMOS
Relationship between VGS and IDS in SiPMOS
Summary comparison between GNRCMOS and SiCMOS
PAGE
63
64
67
xi
LIST OF FIGURES
FIGURE NO.
TITLE
1.1
Example of an ex foliated graphene flake
2.1
a heterojunction between two ”zigzag GNRs Schematics of a
GNR-FET”.
Atomic structure of an armchair GNR
the electronic structure of armchair
Comparisons of EG versus Width for GNRs and CNTs
Spin density maps
”chemically derived for graphene nanoribbon to sub-10-nm”
Graphene Nanoribbon with interesting morphologies and
graphene-junctions
”GNR from CNT ”
Schematics of fabrication for graphene channel: (a) The
transferred graphene films, (b) e-beam irradiation on the bi-layer
resists, (c) pattern transfer to polymethyl methacrylate (PMMA)
resists with XR-1541 barriers, (d) reactive ion etching (RIE), (e)
lift-off process, and (f) cross-sectional view after RIE
”GNRs drive by STM lithography”
”Atomic resolutions STM image”
the narrowest GNR produced by lithography patterning, of 2.5
nm width.
Single gate (Bottom gate electrode) GNRFET
Single gate (Top gate electrode) GNRFET
”Wrapped Gate GNRFET”
Double gate graphene Nanoribbon
Schottky-barrier GNRFET
MOSFET-like GNRFET
MOS structure
Doping of silicon semiconductor
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
2.16
2.17
2.18
2.19
2.20
PAGE
5
12
13
14
14
16
17
18
20
21
23
24
25
26
27
27
28
30
31
32
34
xii
2.21
2.22
2.23
2.24
2.25
2.26
2.27
2.28
2.29
2.30
2.31
2.32
2.33
2.34
”p-n semiconductor junction”
The structures of eight allotrope of carbon
”p- and n-FETs on a single CNT”
carbon nanotube CMOS
the voltage transfer characteristics
”VTC for CNTFET”
the CMOS inverter
structure inverter
Schematic of a back gated 2D graphene FET fabrication
IDS as a function of VG at VDS = 20 mV for short-channel
saturating of graphen
characteristics of 2D epitaxial graphene FETs
showing uniform intensity over large for I-V” . [1]
”Schematic band diagram of a graphene channel”
35
36
37
38
39
40
40
41
42
43
44
45
46
47
3.1
3.2
3.3
Schematic CMOS structure
Schematic CMOS structure of inverter
Flow chart
51
52
53
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
graphene nanoribbon
graphene nanoribbon
I-V GNRCMOS
I-V GNRCMOS different VGS
graphene nanoribbon
Relationships between VIN and VOU T in GNRCOMS (VTC)
Relationships between VIN and VOU T (VTC) SiCMOS
VTC of both GNRCMOS and SiCMOS invertors nanoribbon
60
61
61
62
62
65
65
66
xiii
LIST OF ABBREVIATIONS
SB
–
Schottky Barrier
SEM
–
Scanning Electron Microscope
VTC
–
Voltage Transfer Characteristic
SWNT
–
Single Wall Nanotube
SPINFET
–
Spin Field Effect Transistor
Q1D
–
Quasi-One-Dimensional
Q2D
–
Quasi-Two-Dimensional
PMOS
–
P Channel Metal-Oxide-Semiconductor Swing
NMOS
–
N Channel Metal-Oxide-Semiconductor
PTM
–
Predictive Technology Model
pFET
–
Ptype Field Effect Transistor
SPICE
–
Simulation Program Integrated Circuits Especially
O
–
Ohmic
ND
–
Nondegenerate
nFET
–
Ntype Field Effect Transistor
NEGF
–
Non-Equilibrium Green Function
MWNT
–
Multiwall Nanotube
MOSFET
–
Metal-Oxide-Semiconductor Field-Effect Transistor
MOS
–
Metal-Oxide-Semiconductor
ITRS
–
International Technology Roadmap for Semiconductor
IC
–
Integrated Circuit
HFET
–
Heterojunction Field Effect Transistor
GNR
–
Graphene Nanoribbon
xiv
DOS
–
Density of state
DIBL
–
Drain-Induced Barrier Lowering
DC
–
Direct Current
D
–
Degenerate
CVD
–
Chemical Vapour Deposition
CNFET
–
Carbon Nanotube Field-Effect Transistor
CMOS
–
Complementary Metal-Oxide-Semiconductor
CNT
–
Carbon Nanotube
AC
–
Alternative Current
ABM
–
Analog Behavioural Modeling
–
xv
LIST OF SYMBOLS
σ
–
Conductivity
γ
–
Fitting parameter
Γ
–
Gamma function
=
–
Fermi-Dirac function
ψ
–
Wavefunction
VT
–
Threshold voltage
Vt
–
Thermal voltage
VGS
–
Gate to source voltage
VDS
–
Drain to source voltage
VDD
–
Supply voltage
W
–
Width
Vch
–
Channel voltage
Vc
–
Critical voltage
vth
–
Thermal velocity
vsat
–
Saturation velocity
vinj
–
Injection velocity
vi
–
Intrinsic velocity
vf
–
Fermi velocity
vd
–
Drift velocity
v
–
Carrier velocity
U
–
Potential energy
µ∞
–
Intrinsic mobility
µef f
–
Effective mobility
xvi
µB
–
Ballistic mobility
µB
–
Mobility
T
–
Temperature
W
–
Gate oxide thickness
t
–
C-C bonding energy
W
–
Quantum resistance
Ro
–
Ohmic resistance
Rchannel
–
Channel resistance
Rc
–
Contact resistance
R
–
resistance
r
–
Signal resistance
Q
–
Total number of charge
r
–
Signal resistance
q
–
Number of charge
p
–
Momentum
ρ
–
Resistivity
Nc
–
Effective density of state
η
–
Normalized Fermi energy
n
–
Carrier concentration
m∗
–
Effective mass
Lind
–
Inductance
L
–
Length
`ef f
–
Effective mean free path
`B
–
Ballistic mean free path
`
–
Mean free path
kB
–
Boltzmann Constant
k
–
Wavevector
Isat
–
Saturation current
IDS
–
Drain to source current
h
–
Plank’s constant
xvii
G
–
Conductance
F
–
Carrier force
Ev
–
Valence band
Eg
–
Bandgap energy
EF
–
Fermi energy
E
–
energy
εo
–
Vacuum permittivity
EC
–
Conduction band
εc
–
Critical electric field
ε
–
Electric field
Do
–
Metallic density of state
D(E)
–
Density of state
d
–
Diameter
CQ
–
Quantum capacitance
CC
–
Oxide capacitance
CL
–
Load capacitance
Ci nt
–
Intrinsic capacitance
CGS
–
Gate to source capacitance
CGD
–
Gate to drain capacitance
Cg
–
Gate capacitance
Cext
–
Extrinsic capacitance
CDB
–
Drain to bulk capacitance
C
–
Capacitance
A
–
Area cross section
acc
–
Nearest C-C bonding distance
a
–
Vector of lattice
–
xviii
LIST OF APPENDICES
APPENDIX
A
TITLE
PUBLICATIONS
PAGE
77