Fundamentals of silicon carbide technology : growth, characterization, devices and applications

A comprehensive introduction and up-to-date reference to SiC power semiconductor devices covering topics from material properties to applications

Based on a number of breakthroughs in SiC material science and fabrication technology in the 1980s and 1990s, the first SiC Schottky barrier diodes (SBDs) were released as commercial products in 2001. The SiC SBD market has grown significantly since that time, and SBDs are now used in a variety of power systems, particularly switch-mode power supplies and motor controls. SiC power MOSFETs entered commercial production in 2011, providing rugged, high-efficiency switches for high-frequency power systems. In this wide-ranging book, the authors draw on their considerable experience to present both an introduction to SiC materials, devices, and applications and an in-depth reference for scientists and engineers working in this fast-moving field . Fundamentals of Silicon Carbide Technology covers basic properties of SiC materials, processing technology, theory and analysis of practical devices, and an overview of the most important systems applications. Specifically included are:

A complete discussion of SiC material properties, bulk crystal growth, epitaxial growth, device fabrication technology, and characterization techniques. Device physics and operating equations for Schottky diodes, pin diodes, JBS/MPS diodes, JFETs, MOSFETs, BJTs, IGBTs, and thyristors. A survey of power electronics applications, including switch-mode power supplies, motor drives, power converters for electric vehicles, and converters for renewable energy sources. Coverage of special applications, including microwave devices, high-temperature electronics, and rugged sensors. Fully illustrated throughout, the text is written by recognized experts with over 45 years of combined experience in SiC research and development.

This book is intended for graduate students and researchers in crystal growth, material science, and semiconductor device technology. The book is also useful for design engineers, application engineers, and product managers in areas such as power supplies, converter and inverter design, electric vehicle technology, high-temperature electronics, sensors, and smart grid technology.

Author Notes

Tsunenobu Kimoto, Department of Electronic Science and Engineering, Kyoto University, Japan.
Professor Kimoto has been involved in SiC research for more than 20 years and his research activity in this field covers growth, optical and electrical characterization, device processing, device design and fabrication. He has published more than 300 papers in international journals and has presented more than 50 invited talks at international conferences. He was a guest editor of the 2008 SiC special issues of IEEE Transactions on Electron Devices.

James A Cooper, School of Electrical and Computer Engineering, Purdue University, Indiana, USA
Professor Cooper was a member of technical staff at Bell Laboratories for ten years where he was principal designer of AT&T's first microprocessor and investigated nonlinear transport in silicon inversion layers. His research at Purdue has centered on semiconductor device physics and characterization, focusing primarily on III-V materials and silicon carbide. He has co-authored over 250 technical papers and conference presentations.

About the Authors	p. xi
Prelate	p. xiii
1 Introduction	p. 1
1.1 Progress in Electronics	p. 1
1.2 Features and Brief History of Silicon Carbide	p. 3
1.2.1 Early History	p. 3
1.2.2 Innovations in SiC Crystal Growth	p. 4
1.2.3 Promise and Demonstration of SiC Power Devices	p. 5
1.3 Outline of This Book	p. 6
References	p. 6
2 Physical Properties of Silicon Carbide	p. 11
2.1 Crystal Structure	p. 11
2.2 Electrical and Optical Properties	p. 16
2.2.1 Band Structure	p. 16
2.2.2 Optical Absorption Coefficient and Refractive Index	p. 18
2.2.3 Impurity Doping and Carrier Density	p. 20
2.2.4 Mobility	p. 23
2.2.5 Drift Velocity	p. 27
2.2.6 Breakdown Electric Field Strength	p. 28
2.3 Thermal and Mechanical Properties	p. 30
2.3.1 Thermal Conductivity	p. 30
2.3.2 Phonons	p. 31
2.3.3 Hardness and Mechanical Properties	p. 32
2.4 Summary	p. 32
References	p. 33
3 Bulk Growth of Silicon Carbide	p. 39
3.1 Sublimation Growth	p. 39
3.1.1 Phase Diagram of Si-C	p. 39
3.1.2 Basic Phenomena Occurring during the Sublimation (Physical Vapor Transport) Method	p. 39
3.1.3 Modeling and Simulation	p. 44
3.2 Poly type Control in Sublimation Growth	p. 46
3.3 Detect Evolution and Reduction in Sublimation Growth	p. 50
3.3.1 Stacking Faults	p. 50
3.3.2 Micropipe Defects	p. 51
3.3.3 Threading Screw Dislocation	p. 53
3.3.4 Threading Edge Dislocation and Basal Plane Dislocation	p. 54
3.3.5 Defect Reduction	p. 57
3.4 Doping Control in Sublimation Growth	p. 59
3.4.1 Impurity Incorporation	p. 59
3.4.2 n-Type Doping	p. 61
3.4.3 p-Type Doping	p. 61
3.4.4 Semi-Insulating	p. 62
3.5 High-Temperature Chemical Vapor Deposition	p. 64
3.6 Solution Growth	p. 66
3.7 3C-SiC Wafers Grown by Chemical Vapor Deposition	p. 67
3.8 Watering and Polishing	p. 67
3.9 Summary	p. 69
References	p. 69
4 Epitaxial Growth of Silicon Carbide	p. 75
4.1 Fundamentals of SiC Homoepitaxy	p. 75
4.1.1 Polytype Replication in SiC Epitaxy	p. 75
4.1.2 Theoretical Model of SiC Homoepitaxy	p. 78
4.1.3 Growth Rate and Modeling	p. 83
4.1.4 Surface Morphology and Step Dynamics	p. 87
4.1.5 Reactor Design for SiC Epitaxy	p. 89
4.2 Doping Control in SiC CVD	p. 90
4.2.1 Background Doping	p. 90
4.2.2 n-Type Doping	p. 91
4.2.3 p-Type Doping	p. 92
4.3 Defects in SiC Epitaxial Layers	p. 93
4.3.1 Extended Defects	p. 93
4.3.2 Deep Levels	p. 102
4.4 Fast Homoepitaxy of SiC	p. 105
4.5 SiC Homoepitaxy on Non-standard Planes	p. 107
4.5.1 SiC Homoepitaxy- on Nearly On-Axis (0001)	p. 107
4.5.2 SiC Homoepitaxy on Non-basal Planes	p. 108
4.5.3 Embedded Homoepitaxy of SiC	p. 110
4.6 SiC Homoepitaxy by Other Techniques	p. 110
4.7 Heteroepitaxy of 3C-SiC	p. 111
4.7.1 Heteroepitaxial Growth of 3C-SiC on Si	p. 111
4.7.2 Heteroepitaxial Growth of 3C-SiC on Hexagonal SiC	p. 114
4.8 Summary	p. 114
References	p. 115
5 Characterization Techniques and Defects in Silicon Carbide	p. 125
5.1 Characterization Techniques	p. 125
5.1.1 Photoluminescence	p. 126
5.1.2 Raman Scattering	p. 134
5.1.3 Hall Effect and Capacitance-Voltage Measurements	p. 136
5.1.4 Carrier Lifetime Measurements	p. 137
5.1.5 Detection of Extended Defects	p. 142
5.1.6 Detection of Point Defects	p. 150
5.2 Extended Defects in SiC	p. 155
5.2.1 Major Extended Defects in SiC	p. 155
5.2.2 Bipolar Degradation	p. 156
5.2.3 Effects of Extended Defects on SiC Device Performance	p. 161
5.3 Point Defects in SiC	p. 165
5.3.1 Major Deep Levels in SiC	p. 165
5.3.2 Carrier Lifetime Killer	p. 174
5.4 Summary	p. 179
References	p. 180
6 Device Processing of Silicon Carbide	p. 189
6.1 Ion Implantation	p. 189
6.1.1 Selective Doping Techniques	p. 190
6.1.2 Formation of an n-Type Region by Ion Implantation	p. 191
6.1.3 Formation of a p-Type Region by Ion Implantation	p. 197
6.1.4 Formation of a Semi-Insulating Region by Ion Implantation	p. 200
6.1.5 High-Temperature Annealing and Surface Roughening	p. 201
6.1.6 Defect Formation by Ion Implantation and Subsequent Annealing	p. 203
6.2 Etching	p. 208
6.2.1 Reactive Ion Etching	p. 208
6.2.2 High-Temperature Gas Etching	p. 211
6.2.3 Wet Etching	p. 212
6.3 Oxidation and Oxide/SiC Interface Characteristics	p. 212
6.3.1 Oxidation Rate	p. 213
6.3.2 Dielectric Properties of Oxides	p. 215
6.3.3 Structural and Physical Characterization of Thermal Oxides	p. 217
6.3.4 Electrical Characterization Techniques and Their Limitations	p. 219
6.3.5 Properties of the Oxide/SiC Interface and Their Improvement	p. 234
6.3.6 Intetface Properties of Oxide/SiC an Various Faces	p. 241
6.3.7 Mobility-Limiting Factors	p. 244
6.4 Metallization	p. 248
6.4.1 Schottky Contacts on n-Type and p-Type SiC	p. 249
6.4.2 Ohmic Contacts to n-Type and p-Type SiC	p. 255
6.5 Summary	p. 262
References	p. 263
7 Unipolar and Bipolar Power Diodes	p. 277
7.1 Introduction to SiC Power Switching Devices	p. 277
7.1.1 Blocking Voltage	p. 277
7.1.2 Unipolar Power Device Figure of Merit	p. 280
7.1.3 Bipolar Power Device Figure of Merit	p. 281
7.2 Schottky Barrier Diodes (SBDs)	p. 282
7.3 pn and pin Junction Diodes	p. 286
7.3.1 High-Level Injection and the Ambipolar Diffusion Equation	p. 288
7.3.2 Carrier Densities in the "i" Region	p. 290
7.3.3 Potential Drop across the "i" Region	p. 292
7.3.4 Current-Voltage Relationship	p. 293
7.4 Junction-Barrier Schottky (JBS) and Merged pin-Schottky (MPS) Diodes	p. 296
References	p. 300
8 Unipolar Power Switching Devices	p. 301
8.1 Junction Field-Effect Transistors (JFETs)	p. 301
8.1.1 Pinch-Off Voltage	p. 302
8.1.2 Current- Voltage Relationship	p. 303
8.1.3 Saturation Drain Voltage	p. 304
8.1.4 Specific On-Resistance	p. 305
8.1.5 Enhancement-Mode and Depletion-Mode Operation	p. 308
8.1.6 Power JFET Implementations	p. 311
8.2 Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFETs)	p. 312
8.2.1 Review of MOS Electrostatics	p. 312
8.2.2 MOS Electrostatics with Split Quasi-Fermi Levels	p. 315
8.2.3 MOSFET Current-Voltage Relationship	p. 316
8.2.4 Saturation Drain Voltage	p. 319
8.2.5 Specific On-Resistance	p. 319
8.2.6 Power MOSFET Implementations; DMOSFETs and UMOSFETs	p. 320
8.2.7 Advanced DMOSFET Designs	p. 321
8.2.8 Advanced UMOS Designs	p. 324
8.2.9 Threshold Voltage Control	p. 326
8.2.10 Inversion Layer Electron Mobility	p. 329
8.2.11 Oxide Reliability	p. 339
8.2.12 MOSFET Transient Response	p. 342
References	p. 350
9 Bipolar Power Switching Devices	p. 353
9.1 Bipolar- Junction Transistors (BJTs)	p. 353
9.1.1 Internal Currents	p. 353
9.1.2 Gain Parameters	p. 355
9.1.3 Terminal Currents	p. 357
9.1.4 Current-Voltage Relationship	p. 359
9.1.5 High-Current Effects in the Collector: Saturation and Quasi-Saturation	p. 360
9.1.6 High-Current Effects in the Base: the Rittner Effect	p. 366
9.1.7 High-Current Effects in the Collector: Second Breakdown and the Kirk Effect	p. 368
9.1.8 Common Emitter Current Gain: Temperature Dependence	p. 370
9.1.9 Common Emitter Current Gain: the Effect of Recombination	p. 371
9.1.10 Blocking Voltage	p. 373
9.2 Insulated-Gate Bipolar Transistors (IGBTs)	p. 373
9.2.1 Current-Voltage Relationship	p. 374
9.2.2 Blocking Voltage	p. 384
9.2.3 Switching Characteristics	p. 385
9.2.4 Temperature Dependence of Parameters	p. 391
9.3 Thyristors	p. 392
9.3.1 Forward Conducting Regime	p. 393
9.3.2 Forward Blocking Regime and Triggering	p. 398
9.3.3 The Turn-On Process	p. 404
9.3.4 dV/dt Triggering	p. 406
9.3.5 The d1/dt Limitation	p. 407
9.3.6 The Turn-Off Process	p. 407
9.3.7 Reverse-Blocking Mode	p. 415
References	p. 415
10 Optimization and Comparison of Power Devices	p. 417
10.1 Blocking Voltage and Edge Terminations for SiC Power Devices	p. 417
10.1.1 Impact Ionization and Avalanche Breakdown	p. 418
10.1.2 Two-Dimensional Field Crowding and Junction Curvature	p. 423
10.1.3 Trench Edge Terminations	p. 424
10.1.4 Beveled Edge Terminations	p. 425
10.1.5 Junction Termination Extensions (JTEs)	p. 427
10.1.6 Floating Field-Ring (FFR) Terminations	p. 429
10.1.7 Multiple-Floating-Zone (MFZ) JTE and Space-Modulated (SM) JTE	p. 432
10.2 Optimum Design of Unipolar Drift Regions	p. 435
10.2.1 Vertical Drift Regions	p. 435
10.2.2 Lateral Drift Regions	p. 438
10.3 Comparison of Device Performance	p. 440
References	p. 443
11 Applications of Silicon Carbide Devices in Power Systems	p. 445
11.1 Introduction to Power Electronic Systems	p. 445
11.2 Basic Power Converter Circuits	p. 446
11.2.1 Line-Frequence Phase-Controlled Rectifiers and Inverters	p. 446
11.2.2 Switch-Mode DC-DC Converters	p. 450
11.2.3 Switch-Mode Inverters	p. 453
11.3 Power Electronics for Motor Drives	p. 458
11.3.1 Introduction to Electric Motors and Motor Drives	p. 458
11.3.2 DC Motor Drives	p. 459
11.3.3 Induction Motor Drives	p. 460
11.3.4 Synchronous Motor Drives	p. 465
11.3.5 Motor Drives for Hybrid and Electric Vehicles	p. 468
11.4 Power Electronics for Renewable Energy	p. 471
11.4.1 Inverters for Photovoltaic Power Sources	p. 471
11.4.2 Converters for Wind Turbine Power Sources	p. 472
11.5 Power Electronics for Switch-Mode Power Supplies	p. 476
11.6 Performance Comparison of SiC and Silicon Power Devices	p. 481
References	p. 486
12 Specialized Silicon Carbide Devices and Applications	p. 487
12.1 Microwave Devices	p. 487
12.1.1 Metal-Semiconductor Field-Effect Transistors (MESFETs)	p. 487
12.1.2 Static Induction Transistors (SITs)	p. 489
12.1.3 Impact Ionization Avalanche Transit-Time (1MPATT) Diodes	p. 496
12.2 High-Temperature Integrated Circuits	p. 497
12.3 Sensors	p. 499
12.3.1 Micro-Electro-Mechanical Sensors (MEMS)	p. 499
12.3.2 Gas Sensors	p. 500
12.3.3 Optical Detectors	p. 504
References	p. 509
Appendix A Incomplete Dopant Ionization in 4H-SiC	p. 511
References	p. 515
Appendix B Properties of the Hyperbolic Functions	p. 517
Appendix C Major Physical Properties of Common SiC Polytypes	p. 521
C.1 Properties	p. 521
C.2 Temperature and/or Doping Dependence of Major Physical Properties	p. 522
References	p. 523
Index	p. 525

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