Nitride Semiconductor Technology
Power Electronics and Optoelectronic Devices

Preface xi

Acknowledgments xv

1 Introduction to Gallium Nitride Properties and Applications 1
Fabrizio Roccaforte and Mike Leszczynski

1.1 Historical Background 1

1.2 Basic Properties of Nitrides 4

1.2.1 Microstructure and Related Issues 7

1.2.2 Optical Properties 13

1.2.3 Electrical Properties 16

1.2.4 Two-Dimensional Electron Gas (2DEG) in AlGaN/GaN Heterostructures 19

1.3 Applications of GaN-Based Materials 23

1.3.1 Optoelectronic Devices 24

1.3.2 Power- and High-Frequency Electronic Devices 26

1.4 Summary 30

Acknowledgments 31

References 31

2 GaN-Based Materials: Substrates, Metalorganic Vapor-Phase Epitaxy, and Quantum Well Properties 41
Ferdinand Scholz, Michal Bockowski, and Ewa Grzanka

2.1 Introduction 41

2.2 Bulk GaN Growth 42

2.2.1 Hydride Vapor-Phase Epitaxy (HVPE) 43

2.2.2 Sodium Flux Growth Method 45

2.2.3 Ammonothermal Growth 46

2.3 MOVPE Growth 51

2.3.1 Basics About Nitride MOVPE 54

2.3.2 Epitaxy on Foreign Substrates 58

2.3.2.1 Sapphire as a Foreign Substrate 58

2.3.2.2 GaN on SiC and Si 60

2.3.3 Defect Reduction by ELOG, FACELO, etc. 62

2.3.4 In Situ ELOG by SiN Deposition 64

2.3.5 Doping of Nitrides 64

2.3.6 Growth of Other Binary and Ternary Nitrides 67

2.4 InGaN QWs: Growth and Decomposition 72

2.4.1 Growth of InGaN QWs on Polar, Nonpolar, and Semipolar GaN Substrates 72

2.4.2 Origins of In Fluctuations 75

2.4.3 Homogenization of InGaN QWs 78

2.4.4 Decomposition of the QWs 79

2.5 Summary 82

Acknowledgments 82

References 83

3 GaN-Based HEMTs for Millimeter-wave Applications 99
Kathia Harrouche and Farid Medjdoub

3.1 Introduction 99

3.2 Targeted Applications for GaN Millimeter-wave Devices 99

3.2.1 High-Power Amplification 100

3.2.2 Broadband Amplifiers 102

3.2.3 5G 103

3.2.3.1 GaN for 5G 104

3.2.3.2 GaN Base Station PAs 106

3.2.3.3 Moving Forward to 6G 108

3.3 GaN-based Material Designs for Millimeter-wave Applications 108

3.3.1 Intrinsic Characteristics and Comparison with Other Materials for RF Devices 108

3.3.2 Specific Material Systems for RF Devices 114

3.4 Device Design and Fabrication of Millimeter-wave GaN Devices 116

3.4.1 Description of Key Processing Steps for Various GaN Device Designs 116

3.4.1.1 Device Scaling for Millimeter Wave 116

3.4.1.2 T-shaped Gate Design 116

3.4.1.3 Advanced Ohmic Contact Technology 117

3.4.1.4 N-polar GaN HEMTs 118

3.4.1.5 AlN-Based Device Performances 119

3.4.1.6 InAlGaN-Based Device Performances 121

3.4.2 State-of-the-art Millimeter-wave GaN Transistors 122

3.5 Overview of MMIC Power Amplifiers 123

3.5.1 MMIC Technology Using III-N Devices 123

3.5.1.1 III–V Material-Based MMIC Technology 123

3.5.1.2 Power Amplifiers 124

3.5.1.3 Low-Noise Amplifier 125

3.5.2 MMIC Examples from Ka-band to D-band Frequencies 125

3.6 Summary 126

References 127

4 Technologies for Normally-off GaN HEMTs 137
Giuseppe Greco, Patrick Fiorenza, Ferdinando Iucolano, and Fabrizio Roccaforte

4.1 Introduction 137

4.1.1 Threshold Voltage in AlGaN/GaN HEMTs 138

4.2 GaN HEMT “Cascode” 140

4.3 “True” Normally-off HEMT Technologies 142

4.3.1 Recessed-gate HEMT 142

4.3.2 Fluorinated HEMT 145

4.3.3 Recessed-gate Hybrid MISHEMT 149

4.3.4 p-GaN Gate HEMT 155

4.4 Other Approaches 163

4.5 Summary 164

Acknowledgments 165

References 165

5 Vertical GaN Power Devices 177
Srabanti Chowdhury and Dong Ji

5.1 Introduction 177

5.2 Vertical GaN Devices for Power Conversion 177

5.3 Vertical GaN Transistors 178

5.3.1 Current Aperture Vertical Electron Transistor (CAVET) 178

5.3.2 Vertical MOSFETs 182

5.4 High-Voltage Diodes in GaN 185

5.5 Avalanche Electroluminescence in GaN P–N Diodes 186

5.6 Impact Ionization Coefficients in GaN 188

5.6.1 Impact of Impact Ionization Studies on Predictive Modeling 193

5.7 Summary 193

Acknowledgments 193

References 194

6 Reliability Issues in GaN Electronic Devices 199
Milan Ťapajna and Christian Koller

6.1 Introduction 199

6.1.1 Reliability Testing and Failure Analysis of GaN HEMTs 200

6.2 Reliability of GaN HEMTs for RF Applications 204

6.2.1 AlGaN/GaN HEMTs 204

6.2.1.1 Trapping Effects 204

6.2.1.2 Gate-edge Degradation 207

6.2.1.3 Hot Electron Degradation 209

6.2.2 InAlN/GaN HEMTs 211

6.2.2.1 Hot Electron Degradation 212

6.2.2.2 Role of Hot Phonons 214

6.2.3 Thermal Issues in RF GaN HEMTs 215

6.3 Reliability and Robustness of GaN Power Switching Devices 219

6.3.1 Parasitic Effects in the Carbon-Doped GaN Buffer 221

6.3.1.1 Insulation of GaN Buffer by Carbon Doping 221

6.3.1.2 Time-Dependent “Dielectric” Breakdown (TDDB) of the GaN Buffer 223

6.3.1.3 Dynamic R_DS,ON Due to Buffer Trapping 225

6.3.2 Gate Degradation in p-GaN Switching HEMTs 230

6.3.3 V_th Instabilities in GaN MISHEMTs 233

6.3.3.1 Studies of PBTI in MISHEMTs 237

6.4 Summary 241

Acknowledgments 241

References 241

7 Light-Emitting Diodes 253
Amit Yadav, Hideki Hirayama, and Edik U. Rafailov

7.1 Introduction 253

7.2 State-of-the-Art GaN LEDs 254

7.2.1 Blue LEDs 258

7.2.2 Green LEDs 262

7.3 GaN White LEDs: Approaches and Properties 264

7.3.1 Monolithic LEDs 267

7.3.2 Phosphor-Covered LEDs 271

7.4 AlGaN Deep UV LEDs 275

7.4.1 Growth of High-Quality AlN and Increasing in Internal Quantum Efficiency (IQE) 278

7.4.2 AlGaN-based UVC LEDs 281

7.4.3 Increasing the Light Extraction Efficiency (LEE) 282

7.5 Summary 287

Acknowledgments 288

References 288

8 Laser Diodes Grown by Molecular Beam Epitaxy 301
Greg Muziol, Henryk Turski, Marcin Siekacz, Marta Sawicka, and Czeslaw Skierbiszewski

8.1 Introduction 301

8.2 III-N Growth Fundamentals by Plasma-Assisted MBE 303

8.2.1 Role of N-Flux for Efficient InGaN QWs 304

8.3 Wide InGaN QWs – Beyond Quantum-Confined Stark Effect 305

8.4 Long-Living Laser Diodes on Bulk Ammono-GaN 313

8.5 Laser Diodes with Tunnel Junctions 316

8.5.1 Stacks of Vertically Interconnected Laser Diodes 319

8.5.2 Distributed Feedback Laser Diodes 321

8.6 Summary 324

Acknowledgments 324

References 325

9 Edge Emitting Laser Diodes and Superluminescent Diodes 333
Szymon Stanczyk, Anna Kafar, Dario Schiavon, Stephen Najda, Thomas Slight, and Piotr Perlin

9.1 Laser Diode: History and Development 333

9.1.1 Optoelectronics Background 333

9.1.2 Gallium Nitride Technology Breakthroughs 335

9.1.3 Development of Nitride Laser Diodes 337

9.2 Distributed Feedback Laser Diodes 342

9.3 Superluminescent Diodes 348

9.3.1 History of Superluminescent Diode Development 348

9.3.2 Basic SLD Properties 351

9.3.3 Challenges for SLD Optimization 353

9.4 Semiconductor Optical Amplifiers 354

9.5 Summary 357

References 358

10 Green and Blue Vertical-Cavity Surface-Emitting Lasers 367
Yang Mei, Rong-Bin Xu, Huan Xu, and Bao-Ping Zhang

10.1 Introduction 367

10.1.1 Properties and Application of GaN VCSELs 367

10.1.2 Brief History and Current Status of GaN VCSELs 368

10.1.3 GaN VCSELs with Different DBRs 369

10.1.3.1 GaN VCSELs with Hybrid DBR Structure 370

10.1.3.2 GaN VCSELs with Double Dielectric DBR Structure 371

10.2 Efficiency of Heat Dissipation of Different Device Structures 372

10.2.1 Simulation of Heat Profile of the Device 372

10.2.2 Dependence of R_th on Cavity Length 373

10.3 Green VCSELs Based on InGaN QDs 375

10.3.1 Advantages of QDs Compared with QWs 375

10.3.2 Growth and Optical Properties of InGaN QDs 377

10.3.3 Fabrication Process of VCSELs 379

10.3.4 Properties of QD Green VCSELs 379

10.4 Green VCSELs Based on Cavity-Enhanced Emission of Localized States in Blue Emitting InGaN QWs 380

10.4.1 Cavity Effect 380

10.4.2 Properties of Cavity-Enhanced Green VCSELs 381

10.5 Dual-Wavelength Lasing Based on QD-in-QW Active Structure 384

10.5.1 Characteristics of QD-in-QW Structure 384

10.5.2 Lasing Characteristics of VCSELs 386

10.6 Blue VCSELs with Different Lateral Confinements 386

10.6.1 Design of Index-Guided Structure 386

10.6.2 Emission Properties of VCSELs with Lateral Confinement 388

10.7 Summary 389

References 390

11 Integration of 2DMaterials with Nitrides for Novel Electronic and Optoelectronic Applications 397
Filippo Giannazzo, Emanuela Schilirò, Raffaella Lo Nigro, Pawel Prystawko, and Yvon Cordier

11.1 Introduction 397

11.2 Fabrication of 2D Material Heterostructures with Nitride Semiconductors 400

11.2.1 Transfer of 2D Materials Grown on a Foreign Substrate 400

11.2.2 Direct Growth of 2D Materials on Group III-Nitrides 403

11.2.3 2D Materials as Templates for the Growth of Nitride Semiconductor Films 407

11.3 Electronic Devices Based on 2D Materials/GaN Heterojunctions 413

11.3.1 Band-to-band Tunneling Diodes Based on MoS₂/GaN Heterojunctions 413

11.3.2 Hot Electron Transistors with Graphene Base and Al(Ga)N/GaN Emitter 414

11.4 Optoelectronic Devices Based on 2D Material Junctions with GaN 421

11.4.1 GaN LEDs with Graphene-Transparent Conductive Electrodes 421

11.4.2 MoS₂/GaN Deep UV Photodetectors 427

11.5 Applications of Graphene for Thermal Management in GaN HEMTs 428

11.6 Summary 431

Acknowledgments 431

References 432

Index 439

Fabrizio Roccaforte, PhD,is a Senior Researcher of the Italian National Research Council at the Institute for Microelectronics and Microsystems (CNR-IMM) in Catania, Italy. His research interests are in the field of wide band gap semiconductor materials and processing for power electronics devices.

Mike Leszczynski, PhD,is a Professor of the Polish Academy of Sciences at the Institute of High Pressure Physics (Unipress) and a Vicepresident of TopGaN Lasers, Warsaw, Poland. His research interests are nitride semiconductors, optoelectronics, crystal growth, crystal defects, and X-ray diffraction.