Provides in-depth knowledge on molecular electronics and emphasizes the techniques for designing molecular junctions with controlled functionalities This comprehensive book covers the major advances with the most general applicability in the field of molecular electronic devices. It emphasizes new insights into the development of efficient platform methodologies for building such reliable devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication. It also helps to develop an understanding of the device fabrication processes and the characteristics of the resulting electrode-molecule interface. Beginning with an introduction to the subject, Molecular-Scale Electronics: Concept, Fabrication and Applications offers full chapter coverage on topics such as: Metal Electrodes for Molecular Electronics; Carbon Electrodes for Molecular Electronics; Other Electrodes for Molecular Electronics; Novel Phenomena in Single-Molecule Junctions; and Supramolecular Interactions in Single-Molecule Junctions. Other chapters discuss Theoretical Aspects for Electron Transport through Molecular Junctions; Characterization Techniques for Molecular Electronics; and Integrating Molecular Functionalities into Electrical Circuits. The book finishes with a summary of the primary challenges facing the field and offers an outlook at its future. * Summarizes a number of different approaches for forming molecular-scale junctions and discusses various experimental techniques for examining these nanoscale circuits in detail * Gives overview of characterization techniques and theoretical simulations for molecular electronics * Highlights the major contributions and new concepts of integrating molecular functionalities into electrical circuits * Provides a critical discussion of limitations and main challenges that still exist for the development of molecular electronics * Suited for readers studying or doing research in the broad fields of Nano/molecular electronics and other device-related fields Molecular-Scale Electronics is an excellent book for materials scientists, electrochemists, electronics engineers, physical chemists, polymer chemists, and solid-state chemists. It will also benefit physicists, semiconductor physicists, engineering scientists, and surface chemists.
1 Introduction1
References 4
2 Metal Electrodes for Molecular Electronics7
2.1 Single-Molecule Junctions 7
2.1.1 Scanning Probe Microscopy Break Junctions 7
2.1.1.1 Beyond Traditional SPM Break Junctions 13
2.1.1.2 Applications of SPM Beyond Electron Transport 16
2.1.2 Mechanically Controllable Break Junctions 19
2.1.2.1 Work Principle and Advantages 19
2.1.2.2 MCBJ Chip Fabrication 23
2.1.2.3 MCBJ Applications 25
2.1.3 Electromigration Breakdown Junctions 32
2.1.3.1 Device Fabrication 33
2.1.3.2 Gap Size Control 34
2.1.3.3 Electromigration Applications 37
2.1.4 Electrochemical Deposition Junctions 40
2.1.5 Surface-Diffusion-Mediated Deposition Junctions 43
2.2 Ensemble Molecular Junctions 45
2.2.1 Lift-and-Float Approach 45
2.2.2 Liquid Metal Contact 47
2.2.3 Nanopore and Nanowell 50
2.2.4 On-Wire Lithography 52
2.2.5 Transfer Printing Techniques 54
2.2.6 Self-Aligned Lithography 60
2.2.7 Buffer Interlayer-Based Junction 62
2.2.8 On-Edge Molecular Junction 65
2.2.9 Suspended-Wire Molecular Junctions 68
References 71
3 Carbon Electrodes for Molecular Electronics93
3.1 Carbon Nanotube-Based Electrodes 93
3.1.1 Electrical Breakdown 94
3.1.2 Lithography-Defined Oxidative Cutting 98
3.2 Graphene-Based Electrodes 102
3.2.1 Electroburning 103
3.2.2 Dash-Line Lithography 103
3.3 Other Carbon-Based Electrodes 107
References 109
4 Other Electrodes for Molecular Electronics113
4.1 Silicon-Based Electrodes 113
4.2 Polymer-Based Electrodes 116
References 117
5 Novel Phenomena in Single-Molecule Junctions119
5.1 Quantum Interference 119
5.1.1 Prediction of QI Effects 119
5.1.2 Signature of Quantum Interference 120
5.1.3 Different Transport Pathways 123
5.1.4 Chemical Design to Tune Quantum Interference 124
5.2 Coulomb Blockade and Kondo Resonance 125
5.3 Thermoelectricity 128
5.4 ElectronicPlasmonic Conversion 130
References 132
6 Supramolecular Interactions in Single-Molecule Junctions137
6.1 Hydrogen Bonds 137
6.2 Stacking Interactions 140
6.3 HostGuest Interactions 144
6.4 Charge-Transfer Interactions 149
References 152
7 Characterization Techniques for Molecular Electronics157
7.1 Inelastic Electron Tunneling Spectroscopy 157
7.1.1 History and Background 158
7.1.2 IETS Measurement 160
7.1.3 IETS Applications 163
7.2 TemperatureLengthVariable Transport Measurement 166
7.3 Noise Spectroscopy 170
7.3.1 Thermal Noise and Shot Noise 171
7.3.2 GenerationRecombination and Flicker Noise 172
7.3.3 Noise Spectroscopy Measurements 173
7.3.4 Application of Noise Spectroscopy 174
7.4 Optical and Optoelectronic Spectroscopy 180
7.4.1 Raman Spectroscopy 180
7.4.2 UltravioletVisible Spectroscopy 182
7.4.3 X-ray Photoelectron Spectroscopy 183
7.4.4 Ultraviolet Photoelectron Spectroscopy 184
7.5 Data Characterization Approaches 185
7.5.1 Transition Voltage Spectroscopy 185
7.5.1.1 TVS Models 185
7.5.1.2 Applications of TVS 188
7.5.2 One Dimensional (1D), Two Dimensional (2D) Histogram and QuB 191
References 195
8 Theoretical Aspects for Electron Transport Through Molecular Junctions209
8.1 Theoretical Description of the Tunneling Process 209
8.2 Electron Transport Mechanism 212
8.2.1 Coherent Electron Transport Through Molecular Junctions 212
8.2.2 ElectronPhonon Interaction Effects on Transport Mechanism 214
8.3 First-Principles Modeling 215
8.3.1 Introduction to Density Functional Theory 215
8.3.2 CurrentVoltage Characteristics Calculations 217
References 221
9 Integrating Molecular Functionalities into Electrical Circuits225
9.1 Wiring Toward Nanocircuits 225
9.1.1 Backbones as Charge Transport Pathways 226
9.1.1.1 Hydrocarbon Chains 227
9.1.1.2 Metal Containing Compounds 234
9.1.1.3 Porphyrin Arrays 237
9.1.1.4 Carbon Nanotubes 239
9.1.1.5 Biological Wires 241
9.1.2 Conductance of Single Molecules 244
9.1.2.1 Interfacial Coupling 245
9.1.2.2 Energy Level Alignment 250
9.1.2.3 Photon-Assisted Conductance Enhancement 252
9.1.2.4 Molecular Conductance Measurements 256
9.2 Rectification Toward Diodes 258
9.2.1 General Mechanisms for Molecular Rectification 259
9.2.1.1 AviramRatner Model 259
9.2.1.2 KornilovitchBratkovskyWilliams Model 261
9.2.1.3 DattaPaulsson Model 262
9.2.2 Rectification Stemming from Molecules 262
9.2.2.1 DA and DA System 262
9.2.2.2 DA Diblock Molecular System 263
9.2.3 Rectification Stemming from Different Interfacial Coupling 267
9.2.3.1 Different Electrodes 267
9.2.3.2 Anchoring Groups 268
9.2.3.3 Contact Geometry 269
9.2.3.4 Interfacial Distance 269
9.2.4 Other Molecular Rectifiers 270
9.3 Negative Differential Conductance Toward Oscillators 272
9.3.1 Mechanisms for Negative Differential Conductance 272
9.3.2 Measurement of NDC 274
9.3.3 Application of NDC 276
9.4 Gating Toward Molecular Transistors 277
9.4.1 Back Gating for Novel Physical Phenomenon Investigation 277
9.4.2 Side Gating for Electron Transport Control 282
9.4.3 Electrochemical Gating for Efficient Gate Coupling 283
9.5 Switching Toward Memory Devices 284
9.5.1 Switch Stem from Conformation Change 285
9.5.1.1 Electrical Field Induced Switch 285
9.5.1.2 Tunneling Electron (Charge) Triggered Switch 286
9.5.1.3 Mechanical Force Induced Switch 289
9.5.1.4 Chemical Stimuli Triggered Switch (Redox and pH) 290
9.5.1.5 Light-Triggered Switch 293
9.5.2 Electrochemically Gated Switch 297
9.5.3 Spintronics-Based Switch 301
9.5.4 Other Memory Devices 305
9.6 Molecular Computing 306
9.6.1 DNA-Based Computing 306
9.6.2 Molecular Logic Gates 308
9.7 Transduction Toward Molecular Sensors 313
9.7.1 Sensing Based on Chemical Reactions 314
9.7.2 Sensing Based on Biological Interactions 319
9.7.2.1 Nanocarbon-Based Molecular Electronics 321
9.7.2.2 Silicon-Based Devices 327
9.7.3 Sensing Based on Thermoelectrical Conversion 331
9.8 High-Frequency Molecular Devices 333
9.9 Molecular Machines 337
9.9.1 Molecular Motors 337
9.9.2 Molecular Elevators 338
9.9.3 Molecular Scissors 341
9.9.4 Other Multicomponent Mechanical Machines 344
References 347
10 Summary and Perspectives375
10.1 Primary Challenges 377
10.1.1In SituMeasurement 377
10.1.2 Device Fabrication Yield 378
10.1.3 Device-to-Device Variation and Instability 378
10.1.4 Integration Capability 379
10.1.5 Energy Consumption 380
10.1.6 Addressability 380
10.1.7 General Strategies to Meet Challenges 381
10.2 Open Questions 382
10.3 Outlook 384
References 385
Index 389
