Integrated Nanoelectronics (eBook)

Vinod Kumar Khanna received his M.Sc. degree in physics from the University of Lucknow, Lucknow, India, in 1975, and his Ph.D. degree in physics from Kurukshetra University, Kurukshetra, India, in 1988 for the thesis entitled, “Development, Characterization and Modelling of the Porous Alumina Humidity Sensor.” For more than 36 years at CSIR-CEERI, Dr. Khanna has been involved in different research and development projects on thin-film humidity sensors, high-voltage TV deflection transistors, power Darlington transistors for AC motor drives, fast-switching thyristors, high-current and high-voltage rectifiers, neutron dosimetry diodes, power DMOSFET and IGBT, PMOSFET gamma ray dosimeter, microelectromechanical system (MEMS) technology-based microsensors, ion-sensitive field-effect transistors (ISFETs), ISFET-based chemical and biosensors, capacitive MEMS ultrasonic transducer (cMUT), pressure sensors, MEMS gyroscopes, and MEMS hotplate gas sensors. His present research is focused on nanosensors, particularly on the nanotechnological approaches for improving ISFET performance, and the development of dual-gate silicon nanowire ion-sensitive field-effect transistor (Nano-ISFET). He is a life member (Fellow) of the Institution of Electronics & Telecommunication Engineers (IETE), India, and also life member of Indian Physics Association (IPA), Semiconductor Society India (SSI), and Indo-French Technical Association (IFTA). Dr. Khanna has authored 9 previous books and contributed six chapters to edited books. He has authored or co-authored 181 research papers in various reputed international and national journals and conference proceedings ans holds four patents.

Preface 7
Acknowledgments 9
About This Book 10
Contents 11
About the Author 25
Abbreviations, Acronyms, Chemical Symbols and Mathematical Notation 26
1 Getting Started to Explore “Integrated Nanoelectronics” 39
Abstract 39
1.1 What “Integrated Nanoelectronics” Is About? 39
1.2 Subdivision of the Book 40
1.3 Organization of the Book 41
1.3.1 Part I: Preliminaries 41
1.3.2 Part II: CMOS Nanoelectronics 41
1.3.3 Part III: CMOS-Supportive Nanotechnologies 42
1.3.4 Part IV: Beyond CMOS Nanoelectronics 42
1.3.5 Part V: Nanomanufacturing 44
1.4 Discussion and Conclusions 45
Review Exercises 45
References 46
Preliminaries 47
2 Nanoelectronics and Synergistic Nanodisciplines 48
Abstract 48
2.1 Meaning of “Nano” and “Nanometer” 48
2.2 Nanoscience 49
2.3 Nanotechnology 49
2.4 Plurality of Nanosciences and Nanotechnologies 49
2.5 Nanomaterials 50
2.6 Uniqueness and Specialty of Nanomaterials 50
2.6.1 Quantum Size Effect 50
2.6.2 Surface-Area-to-Volume Ratio 51
2.7 Nanoelectronics 52
2.7.1 More Moore Sub-domain 54
2.7.2 More-than-Moore Sub-domain 54
2.7.3 Beyond CMOS Sub-domain 54
2.7.4 Convergence of Nanosciences 54
2.8 Spintronics and Nanomagnetics 56
2.9 Nanophotonics or Nano-optics 56
2.10 Nanomechanics 57
2.11 Nanobiotechnology 58
2.12 Discussion and Conclusions 58
Review Exercises 59
References 60
3 Nanomaterials and Their Properties 61
Abstract 61
3.1 Bewilderment from a Multitude of Nanomaterial Definitions 61
3.2 ISO (International Organization for Standardization) Definitions 62
3.2.1 Nanomaterial 62
3.2.2 Nanoscale 62
3.2.3 Nano-object 62
3.2.3.1 Particle 62
3.2.3.2 Agglomerate 63
3.2.3.3 Aggregate 63
3.2.3.4 Nanoparticle 64
3.2.3.5 Nanoplate 64
3.2.3.6 Nanofibre 64
3.2.3.7 Nanotube 64
3.2.3.8 Nanorod 64
3.2.3.9 Nanowire 64
3.2.3.10 Quantum Dot 64
3.3 EC (European Commission) Definitions 65
3.3.1 Nanomaterial 65
3.3.2 Particle 65
3.3.3 Agglomerate 66
3.3.4 Aggregate 66
3.4 Mechanical Strength of Nanomaterials 66
3.5 Characterizing Parameters for the Influence of Surface Effects on Material Properties 67
3.6 Catalytic Effects of Nanomaterials 68
3.7 Thermal Properties of Nanomaterials 68
3.7.1 Melting Point Depression 68
3.7.2 Negative Thermal Capacity 69
3.8 Exciton Bohr Radius: A Characteristic Length for Quantum Confinement 69
3.9 Electronic and Optical Properties of Nanomaterials 70
3.9.1 Bandgap Broadening of a Spherical Semiconductor Nanocrystal: The Quantum Dot 70
3.9.2 Interaction of Light with Metallic Nanoparticles 73
3.10 Magnetic Properties of Nanomaterials 74
3.10.1 Superparamagnetic Nanoparticles 74
3.10.2 Magnetism in Gold Nanoparticles 75
3.10.3 Giant Magnetoresistance (GMR) Effect 75
3.11 Discussion and Conclusions 75
Review Exercises 76
References 77
CMOS Nanoelectronics 78
4 Downscaling Classical MOSFET 79
Abstract 79
4.1 Moore’s Law 79
4.2 The Classical, Planar, Single-Gate Bulk MOSFETs 80
4.2.1 The MOS Device and its Electrical Characteristics 80
4.2.2 Self-aligned Polysilicon Gate MOS Process 81
4.2.3 Self-aligned Silicide (Salicide) Process 83
4.3 Complementary Metal-Oxide-Semiconductor (CMOS) Technology 83
4.3.1 CMOS Structure and Advantages 83
4.3.2 CMOS NOT Gate 83
4.3.3 CMOS NAND Gate 84
4.3.4 CMOS NOR Gate 85
4.3.5 CMOS Process 87
4.3.6 Shallow Trench Isolation (STI) Process 91
4.4 Scaling Trends of Classical MOSFETs 95
4.4.1 Constant Field Scaling 95
4.4.1.1 The Principle of Constant Field Scaling 95
4.4.1.2 Effects of Constant Field Scaling 95
4.4.1.3 Drawbacks of Constant Field Scaling 98
4.4.1.4 Problems Faced in Constant Field Scaling 98
4.4.2 Constant Voltage Scaling 99
4.4.2.1 Need of Constant Voltage Scaling 99
4.4.2.2 Effects of Constant Voltage Scaling 99
4.4.2.3 Advantages of Constant Voltage Scaling 101
4.4.2.4 Disadvantages of Constant Voltage Scaling 101
4.5 Scaling Limits for Supply and Threshold Voltages in Classical MOSFETs 102
4.5.1 Subthreshold Leakage Current 102
4.5.2 Subthreshold Slope and VDD, VTh Interrelationship 103
4.6 Discussion and Conclusions 105
Review Exercises 105
References 106
5 Short-Channel Effects in MOSFETs 107
Abstract 107
5.1 Meaning of “Short Channel” 107
5.2 Polysilicon Gate Depletion Effect 108
5.3 Gate-First or Gate-Last Fabrication Flow 109
5.4 Threshold Voltage Roll-off and Drain-Induced Barrier Lowering (DIBL) 112
5.5 Velocity Saturation 114
5.6 Carrier Mobility Degradation 115
5.6.1 Horizontal Field Effect 115
5.6.2 Vertical Field Effect 115
5.7 Impact Ionization 116
5.8 Hot Carrier Effects 116
5.8.1 Substrate Hot Electron (SHE) Injection 116
5.8.2 Channel Hot Electron (CHE) Injection 117
5.8.3 Drain Avalanche Hot Carrier (DAHC) Injection 117
5.8.4 Charge Generation Inside SiO2 117
5.9 Random Dopant Fluctuations (RDF) 117
5.10 Overcoming Short-Channel Effects in Classical MOSFETs 117
5.10.1 Avoiding DIBL Effect 117
5.10.2 Reducing Gate Leakage Current 118
5.10.3 Strain Engineering for Enhancing Carrier Mobility 119
5.10.4 Minimization of Hot Carrier Effects 122
5.10.5 Preventing Punch-Through 123
5.10.6 Innovative Structures Superseding Classical MOSFET 125
5.11 Discussion and Conclusions 125
Review Exercises 126
References 127
6 SOI-MOSFETs 128
Abstract 128
6.1 Introduction 128
6.2 SOI Wafer Manufacturing 130
6.2.1 Separation by Implanted Oxygen (SIMOX) Process 130
6.2.2 Bond and Etch-Back SOI (BESOI) Process 130
6.2.3 Smart Cut® Process 132
6.3 Classification of SOI-MOSFETs 134
6.4 Floating Body Effects in SOI-MOSFET 134
6.4.1 Kink Effects in Partially-Depleted SOI-MOSFET 134
6.4.2 Absence of Kink Effects in Fully-Depleted SOI-MOSFET 138
6.5 Disadvantage of SOI Technology: Self-heating Issue 138
6.6 Double-Gate, Multiple-Gate, and Surround Gate MOSFETs 139
6.7 Discussion and Conclusions 139
Review Exercises 139
References 140
7 Trigate FETs and FINFETs 141
Abstract 141
7.1 Introduction 141
7.2 Relooking at MOSFET Concept in Nanoscale 142
7.3 The Path of MOSFET Restructuring 142
7.4 Rotating the SOI-MOSFET by 90° for Making Trigate FET 142
7.5 Advent of FINFET 143
7.6 What About the Source and the Drain of FINFET? 145
7.7 FINFET Versus Trigate FET 146
7.8 FINFET Fabrication 146
7.9 FINFET on SOI or Bulk Silicon Wafers? 146
7.10 FINFET Comparison with Fully-Depleted SOI-MOSFET 153
7.11 Classification of FINFETs 153
7.12 Impact of Random Doping Effects and Other Process Variations on FINFETs 157
7.13 Discussion and Conclusions 157
Review Exercises 158
References 158
CMOS-Supportive Nanotechnologies 160
8 Nanophotonics 161
Abstract 161
8.1 Introduction 161
8.2 Diffraction-Limited Nanophotonics 162
8.2.1 Plasmonics 162
8.2.1.1 Plasmonics for Data Transference Through Optical Interconnections 162
8.2.1.2 Nanoparticle-Enhanced Surface Plasmon Resonance (SPR)-Based Biosensors 164
8.2.2 Photonic Crystals 166
8.2.3 Quantum Dot Lasers 168
8.2.4 Silicon Nanophotonics 170
8.3 Nanophotonics Beyond the Diffraction Limit 170
8.3.1 Near Field, Dressed Photons, and Nanophotonics 170
8.3.2 Relevance of Plasmonics 171
8.3.3 Exciton-Polariton Exchanges 171
8.3.4 Nanophotonic Devices 172
8.4 Discussion and Conclusions 175
Review Exercises 176
References 177
9 Nanoelectromechanical Systems (NEMS) 178
Abstract 178
9.1 Introduction 178
9.2 NEMS Sensor Classification 179
9.3 MEMS Sensors Downscalable to NEMS Version 179
9.3.1 Piezoresistive Sensors 179
9.3.2 Tunneling Sensors 180
9.4 MEMS Sensors Not Downscalable to NEMS Version 182
9.5 CNT-Based Piezoresistive Nanosensors 182
9.6 NEMS Resonators 183
9.6.1 Resonator-Based Mass Sensors 183
9.6.2 Resonator-Based Strain Sensors 185
9.7 NEMS Actuators 185
9.7.1 CNT Nanotweezers 185
9.7.2 Nanogrippers 185
9.7.3 Magnetic Bead Nanoactuator 186
9.7.4 Nanoactuation by Magnetic Nanoparticles and AC Fields 186
9.7.5 Ferroelectric Switching-Based Nanoactuator 186
9.7.6 Optical Gradient Force-Driven NEMS Actuator 186
9.8 NEMS Memories 187
9.9 Discussion and Conclusions 189
Review Exercises 189
References 190
10 Nanobiosensors 192
Abstract 192
10.1 Introduction 192
10.2 Gold Nanoparticle (GNP) Biosensors 192
10.2.1 Gold Nanoparticle-Enhanced Surface Plasmon Resonance (SPR) Biosensor 193
10.2.2 Gold Nanoparticle LSPR Biosensor 195
10.2.3 Gold Nanoparticle-Wired Electrochemical Biosensor 197
10.3 Magnetic Nanoparticle Biosensors 198
10.4 Quantum Dot (QD) Biosensors 200
10.4.1 QD FRET Biosensor 201
10.4.2 QD BRET Biosensor 201
10.4.3 QD Charge Transfer-Coupled Biosensor 201
10.4.4 QD CRET Biosensor 203
10.5 Carbon Nanotube (CNT) Biosensors 205
10.6 Si Nanowire (SiNW) Biosensors 206
10.6.1 SiNW Electrochemical Biosensor 206
10.6.2 SiNW Field-Effect Transistor (FET) Biosensor 206
10.6.3 SiNW Fluorescence Biosensor 208
10.6.4 SiNW Surface-Enhanced Raman Spectroscopy (SERS) Biosensor 208
10.7 Nanocantilever Biosensor 210
10.8 Discussion and Conclusions 210
Review Exercises 210
References 211
11 Spintronics 214
Abstract 214
11.1 Introduction 214
11.1.1 Defining Spintronics 214
11.1.2 Spintronics and Semiconductor Nanoelectronics 215
11.1.3 Branches of Spintronics 216
11.2 Giant Magnetoresistance (GMR) in Magnetic Nanostructures 217
11.3 Magnetic Tunnel Junction (MTJ) 219
11.4 Magnetic Random Access Memory (MRAM) 220
11.5 Spin Transfer Torque Random Access Memory (STT-RAM) 223
11.6 Discussion and Conclusions 223
Review Exercises 224
References 225
Beyond-CMOS Nanoelectronics 226
12 Tunnel Diodes and Field-Effect Transistors 227
Abstract 227
12.1 Introduction 227
12.2 Quantum Mechanical Tunneling Across a P–N Junction 228
12.3 Nondegenerate and Degenerate Semiconductors 229
12.4 Negative Differential Resistance (NDR) 231
12.5 Tunnel Diode (TD) 232
12.5.1 TD Under Zero Bias 232
12.5.2 TD Under Forward Bias 233
12.5.2.1 Step 1: Small Forward Bias 233
12.5.2.2 Step 2: Slightly Larger Forward Bias 234
12.5.2.3 Step 3: Still Larger Forward Bias 234
12.5.2.4 Step 4: Continued Increase in Forward Bias 234
12.5.2.5 Step 5: Further Continuation of Increase in Forward Bias 237
12.5.3 TD Under Reverse Bias 237
12.6 Resonant Tunneling 238
12.7 Resonant Tunneling Diode (RTD) 238
12.7.1 RTD Heterostructure 239
12.7.2 Physical Phenomena in RTD 239
12.7.3 Simplified Operation of RTD 242
12.7.3.1 Low Forward Bias 242
12.7.3.2 Larger Forward Bias 242
12.7.3.3 Still Larger Forward Bias 242
12.7.3.4 Continued Rise of Forward Bias 244
12.7.3.5 Reverse Bias 244
12.8 Advantages of RTD 244
12.9 Challenges of RTD 244
12.10 Applications of RTD 245
12.11 Tunnel Field-Effect Transistor 245
12.11.1 Recalling MOSFET Principle 245
12.11.2 Tunnel FET Principle 245
12.11.3 Tunnel FET Structure 245
12.11.4 Tunnel FET Operation 246
12.11.5 Participation of Valence and Conduction Bands in Tunnel FET Operation 246
12.12 Discussion and Conclusions 248
Review Exercises 248
References 249
13 Tunnel Junction, Coulomb Blockade, and Quantum Dot Circuit 251
Abstract 251
13.1 Introduction 252
13.2 Coulomb Blockade in a Nanocapacitor 252
13.2.1 Energy Required to Transfer a Single Electronic Charge 252
13.2.1.1 Nanocapacitor 253
13.2.1.2 Microcapacitor 253
13.2.1.3 Millicapacitor 254
13.2.2 Change in Energy Stored on Electron Tunneling 254
13.3 Effect of Temperature 256
13.4 Correlation of Uncertainty in the Number of Electrons with Capacitor Size 257
13.5 Modeling the Tunnel Junction 258
13.5.1 Tunnel Resistance 258
13.5.2 A Constant Current Source Exciting a Tunnel Junction 259
13.6 Basic Analysis of Quantum Dot Circuit 261
13.6.1 Electron Tunneling into the Quantum Dot Island Through Tunnel Junction TJb 264
13.6.2 Electron Tunneling off the Quantum Dot Island Through Tunnel Junction TJa 265
13.6.3 Electron Tunneling into the QD Island Through TJa and Tunneling off the QD Island Through TJb 266
13.7 Energy Band Diagram of Tunnel Junction/Quantum Dot/Tunnel Junction Structure 267
13.7.1 Large Quantum Dot 267
13.7.2 Small Quantum Dot 269
13.8 Discussion and Conclusions 272
Review Exercises 272
References 273
14 Single Electronics 274
Abstract 274
14.1 Introduction 274
14.2 Single Electron Transistor Action 275
14.3 Types of Single Electron Transistor Logic 288
14.3.1 Voltage-Based Logic 288
14.3.2 Charge-Based Logic 290
14.4 Digital Logic Gates 290
14.4.1 SET NOT Gate 291
14.4.2 SET AND Gate 292
14.4.3 SET OR Gate 294
14.5 Other Applications 295
14.6 Discussion and Conclusions 296
Review Exercises 296
References 298
15 Semiconductor Nanowire as a Nanoelectronics Platform 299
Abstract 299
15.1 Introduction 299
15.2 Nanowire Growth by Bottom-up and Top-Down Paradigms 299
15.3 Metal-Catalyst-Assisted Vapor–Liquid–Solid (VLS) Method of Nanowire Growth 300
15.4 Synthesis of Single Crystal Si Nanowires of Required Diameters 301
15.5 Laser-Assisted Catalytic Growth and Doping of Si Nanowires 301
15.6 Ohmic Contacts to Si Nanowires 303
15.7 P-N Junction Diodes Made from Crossed Si Nanowires 303
15.8 Bipolar Transistor Made from Crossed Si Nanowires 303
15.9 Field-Effect Transistors Using Si Nanowires 303
15.10 P-Channel, Ge/Si Core/Shell Nanowire Heterostructure Transistor 304
15.11 N-Channel, GaN/AlN/AlGaN Heterostructure Nanowire Transistor 306
15.12 Complementary Inverters Using P-Type and N-Type Si Nanowire Transistors 307
15.13 Nanowire Integration Methods for Building Nanowire Circuits 307
15.14 Discussion and Conclusions 308
Review Exercises 308
References 309
16 Carbon Nanotube-Based Nanoelectronics 310
Abstract 310
16.1 Introduction 310
16.2 Types of Carbon Nanotubes 311
16.3 Geometrical Structure and Chirality of a Carbon Nanotube 311
16.4 Electrical Properties of Carbon Nanotubes 311
16.5 Mechanical Properties of Carbon Nanotubes 315
16.6 Thermal Properties of Carbon Nanotubes 315
16.7 Synthesis of Carbon Nanotubes 315
16.7.1 Arc Discharge 315
16.7.2 Laser Ablation 316
16.7.3 Chemical Vapor Deposition (CVD) 316
16.8 Chirality-Controlled Synthesis of Carbon Nanotubes 318
16.9 Doping-Free Fabrication of CNT FET 318
16.10 Self-aligned Processes for Fabrication of CNT FET 319
16.11 Fabrication of P-Channel CNT FET 320
16.12 Fabrication of N-Channel CNT FET 321
16.13 Complementary Symmetry SWCNT FET Devices 323
16.14 Pass Transistor Logic (PTL) 324
16.15 Discussion and Conclusions 324
Review Exercises 325
References 326
17 Graphene-Based Nanoelectronics 328
Abstract 328
17.1 Introduction 328
17.2 Electrical Properties of Graphene 329
17.3 Mechanical Properties of Graphene 330
17.4 Optical Properties of Graphene 330
17.5 Preparation of Graphene 330
17.5.1 Micromechanical Exfoliation 330
17.5.2 Growth on Metals Followed by Transfer to Insulating Substrates 331
17.5.3 Thermal Decomposition of Silicon Carbide 331
17.5.4 Substrate-Free Deposition 331
17.6 First Graphene Top-Gated Transistor-like Field-Effect Device 332
17.7 High-Frequency Graphene Transistor 332
17.8 Opening a Bandgap in Graphene 332
17.9 GNR Transistor 333
17.10 Graphene Bilayer Transistor 333
17.11 Hexagonal Boron Nitride (h-BN)-Graphene-Hexagonal Boron Nitride FET 334
17.12 Discussion and Conclusions 335
Review Exercises 335
References 336
18 Transition Metal Dichalcogenides-Based Nanoelectronics 337
Abstract 337
18.1 Introduction 337
18.2 Composition and Mechanical Properties of TMDs 338
18.3 Electrical Properties of TMDs 340
18.4 Optical Properties of TMDs 340
18.5 Preparation of TMDs 340
18.5.1 Micromechanical Exfoliation 340
18.5.2 Liquid Exfoliation 341
18.5.3 Low-Temperature Decomposition of Precursors 341
18.5.4 Chemical Vapor Deposition 341
18.6 Single-Layer Dual-Gate MoS2 FET 342
18.7 Bilayer Back-Gated MoS2 FET 342
18.8 Multilayer Dual-Gate MOS2 Transistor 343
18.9 Mobility Dependence on MoS2 Layer Thickness and Contact Quality 344
18.10 Discussion and Conclusions 345
Review Exercises 345
References 346
19 Quantum Dot Cellular Automata (QDCA) 347
Abstract 347
19.1 Introduction: Moving Towards Transistorless Computing Paradigms 347
19.2 Tougaw-Lent Proposition of a Quantum Device 347
19.3 Role of Quantum Dots in the Scheme 348
19.4 The Standard QDCA Cell 348
19.4.1 Four Quantum Dot, Two-Electron Arrangement 348
19.4.2 Null and Polarization States of the QDCA Cell 349
19.4.3 Changing the Polarization States of a QDCA Cell and Reading These States 350
19.5 QDCA Cell Fabrication 350
19.6 Advantages of QDCA Cell 351
19.7 Binary Wire 351
19.8 The 90° Wire 351
19.9 The 45° Wire 352
19.10 QDCA Inverter or NOT Gate 353
19.11 QDCA Majority Voter 354
19.12 QDCA OR Gate 355
19.13 QDCA AND Gate 357
19.14 Clocking of QDCA 358
19.15 Experimental Validation of QDCA Cell and QDCA Logic Functionality 361
19.16 Discussion and Conclusions 362
Review Exercises 362
References 363
20 Nanomagnetic Logic 364
Abstract 364
20.1 Introduction 364
20.2 Departing from Charge-Based Nanoelectronics 364
20.2.1 Charge-Based MOSFET Nanoelectronics 364
20.2.2 Charge-Based QDCA Nanoelectronics 365
20.3 Single-Spin Logic 365
20.4 The Notion of Room-Temperature Nanomagnetic Logic 367
20.5 Magnetic Quantum Cellular Automata (MQCA) 368
20.5.1 MQCA Versus QDCA 368
20.5.2 MQCA and CMOS 368
20.6 Reconfigurable Array of Magnetic Automata (RAMA) 369
20.6.1 RAMA for Logic Gates 369
20.6.2 RAMA as a Memory Array 372
20.7 Discussion and Conclusions 372
Review Exercises 373
References 373
21 Rapid Single Quantum Flux (RFSQ) Logic 375
Abstract 375
21.1 Introduction 375
21.2 Information Storage and Transference in RFSQ Logic 375
21.3 Components and Cells in RFSQ Logic 376
21.3.1 The Buffer Stage 376
21.3.2 Josephson Transmission Line (JTL) 377
21.3.3 Pulse Splitter 378
21.3.4 Non-reciprocal Buffer Stage 379
21.3.5 The Confluence Buffer 379
21.3.6 The SQUID as an R-S Flip-Flop 380
21.4 RFSQ Circuit and Convention 382
21.5 OR Gate 382
21.6 NOT Gate 383
21.7 RFSQ IC Fabrication Techniques 384
21.8 Advantages and Applications of RFSQ Logic 384
21.9 Disadvantages of RFSQ Logic 385
21.10 Discussion and Conclusions 385
Review Exercises 385
References 386
22 Molecular Nanoelectronics 387
Abstract 387
22.1 Introduction 387
22.2 The Idea of Molecular Electronics 387
22.3 Qualifying Characteristics of a Molecular Electronic Device and Related Hurdles 388
22.4 Placement/Positioning and Contacting of Molecules 388
22.4.1 Top Junction Formation by Microscopic Technique 389
22.4.2 Nanogap Electrode Formation by Break Junction Method 389
22.5 Electrical Behavior of Contacts 390
22.6 Conducting Molecular Wires for Interfacing 391
22.7 Insulators for Molecular Devices 391
22.8 N- and P-Type Regions 392
22.9 Molecular Switch 392
22.9.1 Photochromic Switch 392
22.9.2 Redox Switch 392
22.10 Molecular Rectifying Diode 393
22.11 Discussion and Conclusions 398
Review Exercises 399
References 400
Nanomanufacturing 401
23 Top-Down Nanofabrication 402
Abstract 402
23.1 Introduction 402
23.2 Optical Lithography 403
23.2.1 Key Metrics 403
23.2.2 Immersion Lithography 405
23.2.3 Extreme UV (EUV) Lithography 405
23.3 Electron Beam (E-Beam) Lithography 406
23.3.1 The Equipment and Method 406
23.3.2 Proximity Effect 408
23.3.3 Substrate Charging 408
23.3.4 Electron Projection Lithography (EPL) 408
23.4 Soft Lithography 409
23.5 Nanoimprint Lithography (NIL) 411
23.6 Block Copolymer (BCP) Lithography 414
23.7 Scanning Probe Lithography (SPL) 415
23.8 Discussion and Conclusions 415
Review Exercises 416
References 417
24 Bottom-up Nanofabrication 418
Abstract 418
24.1 Introduction 418
24.2 Sol-Gel Process 419
24.3 Vapor Deposition (VD) 421
24.3.1 Physical Vapor Deposition (PVD) 421
24.3.2 Chemical Vapor Deposition (CVD) 423
24.4 Atomic Layer Deposition (ALD) 424
24.4.1 ALD Process 424
24.4.2 Advantages of ALD 426
24.4.3 Disadvantages of ALD 426
24.4.4 Applications of ALD 427
24.4.5 Limitations of ALD 427
24.5 Molecular Self-Assembly 427
24.5.1 Lipid Bilayer Formation by Self-Assembly 428
24.5.2 Types of Molecular Self-Assembly 429
24.6 Driving Factors for Self-Assembly 429
24.6.1 Molecular Motion 429
24.6.2 Intermolecular Forces 429
24.7 Approaches for Self-Assembly 430
24.7.1 Electrostatic Self-Assembly 430
24.7.2 Self-Assembled Monolayers (SAMs) 431
24.8 DNA Nanoengineering 432
24.8.1 DNA Structure 432
24.8.2 DNA Origami 434
24.9 Self Assembly of Nanocomponent Arrays on DNA Scaffolds 435
24.10 Self-Assembled DNA Scaffolds for Nanoelectronic Circuit Boards 435
24.11 Discussion and Conclusions 436
Review Exercises 436
References 438
25 Nanocharacterization Techniques 439
Abstract 439
25.1 Introduction 439
25.2 Scanning Probe Microscopy (SPM) 440
25.2.1 Near-Field Scanning Optical Microscopy (NSOM) 440
25.2.2 Scanning Tunneling Microscopy (STM) 440
25.2.3 Atomic Force Microscopy (AFM) 441
25.3 Electron Microscopy 444
25.3.1 Transmission Electron Microscopy (TEM) 444
25.3.2 Scanning Electron Microscopy (SEM) 445
25.3.3 Field Emission Scanning Electron Microscopy (FESEM) 445
25.3.4 Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) 447
25.3.5 Specimen Preparation for Electron Microscopy 447
25.3.6 Electron Microscope Upkeep and Maintenance 447
25.4 X-Ray Techniques 448
25.4.1 Energy Dispersive X-Ray Analysis (EDX) 448
25.4.2 X-Ray Powder Diffraction (XRD) 448
25.4.3 X-Ray Photoelectron Spectroscopy (XPS) 449
25.5 Fourier Transform Infrared (FT-IR) Spectroscopy 450
25.6 Ultraviolet and Visible (UV-Visible) Absorption Spectroscopy 452
25.7 Raman Spectroscopy 453
25.7.1 Resonance-Enhanced Raman Scattering Spectroscopy 455
25.7.2 Surface-Enhanced Raman Scattering (SERS) Spectroscopy 455
25.7.3 Confocal/Micro Raman Spectroscopy 456
25.8 Photon Correlation Spectroscopy 456
25.9 Zeta Potential Analysis by Laser Doppler Electrophoresis 457
25.10 Laser Doppler Vibrometry (LDV) 458
25.11 Discussion and Conclusions 460
Review Exercises 460
References 462
Index 463