Preface ......................................................... v
About the Editors ............................................. xix
List of Contributors .......................................... xxi
Contents of Volumes in This Set ............................... xxv
CHAPTER 1. Spintronics in GaN and Related Materials
S.J.Pearton, C.R.Abernathy, Y.D.Park, J.M.Zavada
1. Introduction ................................................ 1
2. Potential Semiconductor Materials for Spintronics ........... 2
2.1. Ferromagnetism in Semiconductors ...................... 4
2.2. Computational Approaches .............................. 5
2.3. A1N .................................................. 29
2.4. AlGaN ................................................ 34
2.5. Potential Device Applications ........................ 36
2.6. Issues to be Resolved ................................ 40
References ................................................. 41
CHAPTER 2. Spin-Lattice Relaxation in Magnetic Semiconductor
Nanostructures
Andrey V. Ahimov, Alexey V. Scherbakov,
Dmitri R. Yakovlev
1. Introduction ............................................... 45
1.1. Magnetization and Spin-Phonon Transitions ............ 47
2. Experimental Techniques .................................... 50
2.1. Introduction to Phonon Spectroscopy .................. 51
2.2. Luminescence Detection of Nonequilibrium Acoustic
Phonons in Magnetic Semiconductors ................... 52
2.3. Measurement of Spin-Lattice Relaxation Time .......... 60
3. Spin-Lattice Relaxation in Undoped Quantum Wells ........... 63
4. Spin-Lattice Relaxation in Doped Quantum Wells ............. 69
4.1. 2D Electron Gas ...................................... 70
4.2. 2D Hole Gas .......................................... 75
5. Spin-Lattice Relaxation and Spin Diffusion on Magnetic
Ions ....................................................... 78
5.1. Spin-Lattice Relaxation in Heteromagnetic
Nanostructures ....................................... 80
5.2. Dynamics of Localized Mn Spins in Nanostructures with
Quantum Dots ......................................... 83
6. Conclusions ................................................ 90
References ................................................. 91
CHAPTER 3. Material and Device Issues of AIGaN/GaN High Electron
Mobility Transistors
Peter Kordos
1. Introduction ............................................... 96
2. Material Structure ......................................... 99
2.1. Substrate for GaN High-Electron Mobility
Transistor .......................................... 100
2.2. Freestanding Highly Resistive GaN:Fe Substrate ...... 101
2.3. Highly Resistive GaN Buffer Layer ................... 103
2.4. AlGaN/GaN High-Electron Mobility Transistor
Heterostructure ..................................... 108
2.5. Round-High-Electron Mobility Transistor Quick
Device .............................................. 115
2.6. Photoionization Spectroscopy ........................ 117
2.7. Backgating .......................................... 119
2.8. Passivation ......................................... 122
3. Device Preparation ........................................ 123
3.1. Mesa Etching ........................................ 124
3.2. Ohmic Contacts ...................................... 126
3.3. Schottky Contacts ................................... 126
4. High-Electron Mobility Transistor on Silicon Substrate .... 127
4.1. Device Performance .................................. 128
4.2. Thermal Effects ..................................... 130
4.3. Effect of Surface Passivation on Performance
of AlGaN/GaN/Si High-Electron Mobility
Transistors ......................................... 132
4.4. Effect of Layer Structure on Performance
of AlGaN/GaN/Si High-Electron Mobility Transistor
Before and After Passivation ........................ 137
5. High-Electron Mobility Transistor on SiC Substrate ........ 140
5.1. Impact of Layer Structure on Performance of
Unpassivated AlGaN/GaN/SiC High-Electron Mobility
Transistors ......................................... 141
5.2. Current Collapse of Unpassivated Devices ............ 143
5.3. Bias Stress of Unpassivated Devices ................. 144
6. Conclusions ............................................... 149
References ................................................ 149
CHAPTER 4. Vacuum Nanoelectronics
V. Litovchenko, A. Evtukh
1. Introduction .............................................. 153
2. Physical Bases of Electron Field Emission ................. 155
2.1. Fowler-Nordheim Equation ............................ 155
2.2. Work Function and Electron Affinity ................. 157
2.3. Electron Field Emission from Conductors,
Semiconductors, and Dielectric Films ................ 161
2.4. Electron Field Emission from Structures with
Quantum Wells ....................................... 163
3. Types of Nanostructures and Peculiarities of Electron
Field Emission ...................................... 183
3.1. Electrically Nanostructured Heterogeneous
Emitters ............................................ 183
3.2. Diamond and Diamond Films ........................... 186
3.3. Nanostructured Diamond-Like Carbon Films ............ 189
3.4. Carbon Nanotubes .................................... 197
3.5. Layered Nanostructures with Delta-Doped Layer:
Multilayer Cathodes ................................. 199
3.6. Porous Silicon Layers ............................... 204
3.7. Nanocomposite Si02(Si) Films ........................ 214
3.8. Nanocrystalline Silicon Films ....................... 220
3.9. Electron Field Emission from Some Other
Semiconductors ...................................... 222
4. Vacuum Nanoelectronics Devices ............................ 224
4.1. Triode Field Emitter ................................ 224
4.2. Field Emission Display .............................. 225
5. Summary and Prospects ..................................... 226
References ................................................ 227
CHAPTER 5. Emerging Double-Gate MOSFET Technology
Yongxun Liu, Meishoku Masahara, Eiichi Suzuki
1. Introduction .............................................. 235
2. Double-Gate MOSFET Concept ................................ 239
3. Historical Planar Double-Gate MOSFETs ..................... 241
4. FinFET Technology ......................................... 243
4.1. FinFET Concept ...................................... 243
4.2. Recent Developments in FinFET Technology ............ 244
4.3. Further Challenges .................................. 248
5. FinFET Fabrication by Orientation-Dependent Wet Etching ... 252
5.1. Orientation-Dependent Wet Etching ................... 252
5.2. Ideally Rectangular Cross-Section Si-Fin Channel
FinFETs ............................................. 253
5.3. Threshold Voltage Controllable Four-Terminal
FinFETs ............................................. 259
6. Vertical Double-Gate-MOSFETs .............................. 264
6.1. Research and Development on Vertical
Double-Gate-MOSFETs ................................. 266
6.2. Novel Process to Form Vertical Ultrathin Channels:
Ion-Bombardment-Retarded Etching .................... 267
6.3. Ultrathin Channel Vertical Double-Gate MOSFETs
Fabricated by IBRE .................................. 268
6.4. Threshold Voltage Tuning for Vertical Double-Gate
MOSFETs: Vertical Asymmetric φm DG-MOSFETS .......... 270
6.5. Fabrication of Vertical Double-Gate MOSFETs with
Planar SG MOSFETs ................................... 271
7. Summary ................................................... 274
References ................................................ 274
CHAPTER 6. Room-Temperature Operating Silicon Single-Electron
Transistors
Masumi Saitoh, Toshiro Hiramoto
1. Introduction .............................................. 279
2. Fundamentals of Single-Electron Transistors ............... 280
2.1. Single-Electron Box ................................. 280
2.2. Operation Principle of SETs ......................... 281
2.3. Requirements for SET Operation ...................... 284
2.4. Other SET Characteristics ........................... 285
2.5. Variations of SETs .................................. 285
2.6. Calculation of SET Characteristics .................. 286
2.7. Advantages and Disadvantages of SETs ................ 287
3. Fabrication of Silicon Single-Electron Transistors ........ 287
3.1. Overview ............................................ 288
3.2. Formation by Lithography ............................ 288
3.3. Formation by Self-Assembly .......................... 291
3.4. Approaches for Room-Temperature Operating Silicon
SETs ................................................ 292
3.5. Quantum Mechanical Effects in Silicon SETs .......... 297
3.6. Room-Temperature Operating SETs Made of Other
Materials ........................................... 303
4. Silicon Single-Electron Logic Circuits .................... 303
4.1. CMOS-Like SET Logic ................................. 304
4.2. Key Issues in CMOS-Like SET Logic ................... 309
4.3. Charge State Logic .................................. 312
4.4. SET-Based Memory .................................... 316
5. Summary ................................................... 317
References ................................................ 317
CHAPTER 7. Modeling and Simulation of Modern Semiconductor
Devices for Low-Power and High Performance
Applications
Bipul C. Paul, Kaushik Roy
1. Introduction .............................................. 321
2. Bulk MOS Transistor ....................................... 322
2.1. MOSFET I-V Characteristics .......................... 323
2.2. Leakage Currents .................................... 327
2.3. Capacitances ........................................ 336
3. SOI MOSFET ................................................ 338
3.1. Single-Gate Fully Depleted SOI MOSFETs .............. 338
3.2. Double-Gate SOI MOSFET (DGMOS) ...................... 344
3.3. Asymmetric DGMOSFET ................................. 349
4. Summary ................................................... 356
References ................................................ 356
CHAPTER 8. Electron Transport and Phonons in Quantum Wires
Norihiko Nishiguchi
1. Overview .................................................. 359
2. Electron Scattering by Acoustic Phonons in a
Freestanding Quantum Wire ................................. 362
2.1. Cylindrical Wire of Isotropic Material .............. 362
2.2. Rectangular Wire of Anisotropic Material and
Nonlocal Electron-Phonon Interaction ................ 370
3. Electron Scattering in an Embedded Quantum Wire ........... 381
3.1. Acoustic Phonons in an Embedded Quantum Wire ........ 382
3.2. Confined Modes ...................................... 384
3.3. Interface Modes ..................................... 388
3.4. Extended Modes ...................................... 392
3.5. Electron Scattering Due to Confined and Extended
Acoustic Phonons in a Quantum Wire .................. 400
4. Summary and Discussion .................................... 404
References ................................................ 406
CHAPTER 9. Non-Equilibrium Green Functions in Electronic
Device Modeling
Roger K. Lake, Rajeev R. Pandey
1. Introduction .............................................. 409
2. One Dimensional Transport Through Planar Semiconductor
Devices ................................................... 410
2.1. Nanoelectronic Engineering Modeling (NEMO) .......... 410
2.2. Post NEMO ID Non-Equilibrium Green's Function
(NEGF) Developments ................................. 420
3. Two-Dimensional Transport in Transistors .................. 424
3.1. Recursive Green Function Algorithm for G ............ 426
4. Three-Dimensional Transport Through CNTs, Nanowires,
and Molecules ............................................. 427
5. Green Functions in a Non-orthogonal Basis ................. 427
5.1. The Non-Orthogonal Localized Orbital Basis .......... 427
5.2. Non-Equilibrium Green Functions and Correlation
Functions ........................................... 429
5.3. Boundary Self-Energies .............................. 431
5.4. Current ............................................. 435
6. Conclusion ................................................ 443
References ................................................ 443
CHAPTER 10. Kinetic and Quantum Models in Simulation of Modern
Nanoscale Devices
Alexander I. Fedoseyev, Marek Turowski,
Marek S. Wartak
1. Introduction .............................................. 448
2. Drift-Diffusion with Quantum Corrections .................. 448
2.1. Governing Equations for Simple Drift-Diffusion
Model ............................................... 449
2.2. Analytical Description of Tunneling. Rectangular
Barrier ............................................. 451
2.3. Quantum Tunneling Current Through the Tunnel
Junction ............................................ 452
2.4. Numerical Approach to Tunneling Through the
Barrier ............................................. 455
2.5. Numerical Models of Schottky Contact ................ 456
3. Kinetic Models and Implementation Issues .................. 458
3.1. Multidimensional Kinetic Model for Electron
Transport ........................................... 458
3.2. Validation of Kinetic Model ......................... 460
3.3. Quantum Corrections to Kinetic Boltzmann
Transport Equation .................................. 462
4. Schrodinger Equation Based Approach ....................... 464
4.1. The Stationary Model ................................ 464
4.2. Time-Dependent Model ................................ 465
4.3. Some Applications ................................... 466
5. Non-Equilibrium Green's Function Method ................... 470
5.1. Non-Equilibrium Green's Functions and Dyson
Equations ........................................... 470
5.2. Quantum Boltzmann Equation .......................... 472
5.3. Wigner Function Model ............................... 473
6. Quantum Hydrodynamic (QHD) ................................ 473
7. Description of Simulators ................................. 476
7.1. Nemo ................................................ 476
7.2. CFDRC-TCAD Device Simulator ......................... 478
8. Conclusions ............................................... 480
References ................................................ 481
CHAPTER 11. Quantized Electron Paths in Nano-Structures
I.W. Kings ley, A.M. Song
1. Introduction .............................................. 483
2. Quantum Point Contacts .................................... 485
2.1. Quantized Conductance ............................... 485
2.2. Fabrication ......................................... 486
2.3. Conductance Mechanism ............................... 487
2.4. Electron Flow Paths ................................. 490
3. Simulating Branched Electron Flow ......................... 492
3.1. Simulation Techniques ............................... 492
3.2. High Temperature Simulations ........................ 494
3.3. Adiabatic Transport ................................. 495
4. Angular Probability Distributions ......................... 496
4.1. Calculating APDs .................................... 497
4.2. Effect of QPC Width on APDs ......................... 498
4.3. APDs with Applied Bias .............................. 500
4.4. APDs with Applied Bias and Soft Walls ............... 501
5. New Device Concepts ....................................... 503
5.1. Low Temperature Devices ............................. 503
5.2. Room Temperature Devices ............................ 505
6. Summary and Conclusions ................................... 508
7. Appendix—Effective temperature of a wave packet ........... 508
References ................................................ 510
Index ......................................................... 513
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