Table of Contents

List of Contributors xv

Foreword xvii

Series Preface xix

Preface xxi

Safety and Environment Disclaimer xxiii

1 Introduction to Metalorganic Vapor Phase Epitaxy 1
S.J.C. Irvine and P. Capper

1.1 Historical Background of MOVPE 1

1.2 Basic Reaction Mechanisms 4

1.3 Precursors 8

1.4 Types of Reactor Cell 9

1.5 Introduction to Applications of MOVPE 11

1.5.1 AlN for UV Emitters 11

1.5.2 GaAs/AlGaAs VCSELS 11

1.5.3 Multijunction Solar Cells 12

1.5.4 GaAs and InP Transistors for High‐Frequency Devices 13

1.5.5 Infrared Detectors 14

1.5.6 Photovoltaic and Thermophotovoltaic Devices 14

1.6 Health and Safety Considerations in MOVPE 15

1.7 Conclusions 16

References 16

2 Fundamental Aspects of MOVPE 19
G.B. Stringfellow

2.1 Introduction 19

2.2 Thermodynamics 20

2.2.1 Thermodynamics of MOVPE Growth 20

2.2.2 Solid Composition 24

2.2.3 Phase Separation 29

2.2.4 Ordering 31

2.3 Kinetics 35

2.3.1 Mass Transport 35

2.3.2 Precursor Pyrolysis 36

2.3.3 Control of Solid Composition 37

2.4 Surface Processes 40

2.4.1 Surface Reconstruction 41

2.4.2 Atomic‐Level Surface Processes 42

2.4.3 Effects of Surface Processes on Materials Properties 44

2.4.4 Surfactants 46

2.5 Specific Systems 52

2.5.1 AlGaInP 52

2.5.2 Group III Nitrides 53

2.5.3 Novel Alloys 56

2.6 Summary 59

References 60

3 Column III: Phosphides, Arsenides, and Antimonides 71
H. Hardtdegen and M. Mikulics

3.1 Introduction 71

3.2 Precursors for Column III Phosphides, Arsenides, and Antimonides 73

3.3 GaAs‐Based Materials 74

3.3.1 (AlGa)As/GaAs Properties and Deposition 74

3.3.2 GaInP, (AlGa)InP/GaAs Properties and Deposition 79

3.4 InP‐Based Materials 82

3.4.1 InP Properties and Deposition 82

3.4.2 AlInAs/GaInAs/AlGaInAs Properties and Deposition 83

3.4.3 AlInAs/GaInAs/InP Heterostructures 84

3.4.4 InxGa1–xAsyP1–y Properties and Deposition 84

3.5 Column III Antimonides Properties and Deposition 86

3.5.1 Deposition of InSb, GaSb, and AlSb 87

3.5.2 Deposition of Ternary Column III Alloys (AlGa)Sb and (GaIn)Sb 89

3.5.3 Deposition of Ternary Column V Alloys In(AsSb), GaAsSb 89

3.5.4 Deposition of Quaternary Alloys 90

3.5.5 Epitaxy of Electronic Device Structures 90

3.5.6 Epitaxy of Optoelectronic Device Structures 95

3.6 In Situ Optical Characterization/Growth Control 100

3.7 Conclusions 100

References 101

4 Nitride Semiconductors 109
A. Dadgar and M. Weyers

4.1 Introduction 109

4.2 Properties of III‐Nitrides 110

4.3 Challenges in the Growth of III‐Nitrides 111

4.3.1 Lattice and Thermal Mismatch 111

4.3.2 Ternary Alloys: Miscibility and Compositional Homogeneity 113

4.3.3 Gas‐Phase Prereactions 115

4.3.4 Doping of III‐Nitrides 117

4.4 Substrates 120

4.4.1 Heteroepitaxy on Foreign Substrates 122

4.4.2 GaN Growth on Sapphire 125

4.4.3 III‐N Growth on SiC 126

4.4.4 GaN Growth on Silicon 127

4.5 MOVPE Growth Technology 130

4.5.1 Precursors 130

4.5.2 Reactors and In Situ Monitoring 130

4.6 Economic Importance 136

4.6.1 Optoelectronic Devices 137

4.6.2 Electronic Devices 138

4.7 Conclusions 138

References 138

5 Metamorphic Growth and Multijunction III‐V Solar Cells 149
N.H. Karam, C.M. Fetzer, X.‐Q. Liu, M.A. Steiner, and K.L. Schulte

5.1 Introduction to MOVPE for Multijunction Solar Cells 149

5.1.1 III‐V PV Solar Cell Opportunities and Applications 149

5.1.2 Metamorphic Multijunction Solar Cells 151

5.1.3 Reactor Technology for Metamorphic Epitaxy 154

5.2 Upright Metamorphic Multijunction (UMM) Solar Cells 154

5.2.1 Introduction and History of Upright Metamorphic Multijunctions 154

5.2.2 MOVPE Growth Considerations of UMM 156

5.2.3 Growth and Device Results 158

5.2.4 Challenges and Future Outlook 162

5.3 Inverted Metamorphic Multijunction (IMM) Solar Cells 162

5.3.1 Introduction and History of Inverted Metamorphic Multijunctions 162

5.3.2 MOVPE Growth Considerations of IMM 164

5.3.3 Growth and Device Results 167

5.3.4 Challenges and Future Outlook 169

5.4 Conclusions 169

References 170

6 Quantum Dots 175
E. Hulicius, A. Hospodková, and M. Zíková

6.1 General Introduction to the Topic 175

6.1.1 Definition and History 175

6.1.2 Paradigm of Quantum Dots 176

6.1.3 QD Types 176

6.2 AIIIBV Materials and Structures 178

6.2.1 QDs Embedded in the Structure 178

6.2.2 Semiconductor Materials for Embedded QDs 180

6.3 Growth Procedures 181

6.3.1 Comparison of MBE‐ and MOVPE‐Grown QDs 181

6.3.2 Growth Parameters 182

6.3.3 QD Surrounding Layers 185

6.4 In Situ Measurements 193

6.4.1 Reflectance Anisotropy Spectroscopy of QD Growth 193

6.4.2 Other Supporting In Situ Measurements 197

6.5 Structure Characterization 198

6.5.1 Optical: Photo‐, Magnetophoto‐, Electro‐luminescence, and Spin Detection 198

6.5.2 Microscopies – AFM, TEM, XSTM, BEEM/BEES 200

6.5.3 Electrical: Photocurrent, Capacitance Measurements 202

6.6 Applications 203

6.6.1 QD Lasers, Optical Amplifiers, and LEDs 204

6.6.2 QD Detectors, FETs, Photovoltaics, and Memories 205

6.7 Summary 208

6.8 Future Perspectives 208

Acknowledgment 209

References 209

7 III‐V Nanowires and Related Nanostructures: From Nitrides to Antimonides 217
H.J. Joyce

7.1 Introduction to Nanowires and Related Nanostructures 217

7.2 Geometric and Crystallographic Properties of III‐V Nanowires 219

7.2.1 Crystal Phase 219

7.2.2 Growth Direction, Morphology, and Side‐Facets 220

7.3 Particle‐Assisted MOVPE of Nanowires 222

7.3.1 The Phase of the Particle 222

7.3.2 The Role of the Particle 224

7.3.3 Axial and Radial Growth Modes 226

7.3.4 Self‐Assisted Growth 228

7.4 Selective‐Area MOVPE of Nanowires and Nanostructures 228

7.4.1 The Role of the Mask 229

7.4.2 Axial and Radial Growth Modes 230

7.5 Alternative Techniques for MOVPE of Nanowires 231

7.6 Novel Applications of Nanowires 231

7.7 Concluding Remarks 233

References 234

8 Monolithic III/V integration on (001) Si substrate 241
B. Kunert and K. Volz

8.1 Introduction 241

8.2 III/V‐Si Interface 243

8.2.1 Si Surfaces 243

8.2.2 Interface Formation in the Presence of Impurities and MO Precursors 247

8.2.3 Atomic III/V on Si Interface Structure 249

8.2.4 Antiphase Domains 251

8.2.5 III/V Growth on Si(001) 252

8.3 Heteroepitaxy of Bulk Layers on Si 255

8.3.1 Lattice‐Matched Growth on Si 257

8.3.2 Metamorphic Growth on Blanket Si 258

8.3.3 Selective‐Area Growth (SAG) on Si 264

8.4 Conclusions 282

References 282

9 MOVPE Growth of Cadmium Mercury Telluride and Applications 293
C.D. Maxey, P. Capper, and I.M. Baker

9.1 Requirement for Epitaxy 293

9.2 History 294

9.3 Substrate Choices 295

9.3.1 Orientation 296

9.3.2 Substrate Material 296

9.4 Reactor Design 297

9.4.1 Process Abatement Systems 298

9.5 Process Parameters 299

9.6 Metalorganic Sources 299

9.7 Uniformity 300

9.8 Reproducibility 302

9.9 Doping 302

9.10 Defects 304

9.11 Annealing 307

9.12 In Situ Monitoring 308

9.13 Background for Applications of MOVPE MCT 308

9.13.1 Introduction to Infrared Imaging and Atmospheric Windows 308

9.13.2 MCT Infrared Detector Market in the Modern Era 309

9.14 Manufacturing Technology for MOVPE Photodiode Arrays 311

9.14.1 Mesa Heterojunction Devices (MHJ) 311

9.14.2 Wafer‐Scale Processing 312

9.15 Advanced MCT Technologies 312

9.15.1 Small‐Pixel Technology 313

9.15.2 Higher Operating Temperature (HOT) Device Structures 313

9.15.3 Two‐Color Array Technology 314

9.15.4 Nonequilibrium Device Structures 316

9.16 MOVPE MCT for Scientific Applications 316

9.16.1 Linear‐Mode Avalanche Photodiode Arrays (LmAPDs) in MOVPE 316

9.17 Conclusions and Future Trends for MOVPE MCT Arrays 320

Definitions 321

References 322

10 Cadmium Telluride and Related II‐VI Materials 325
G. Kartopu and S.J.C. Irvine

10.1 Introduction and Historical Background 325

10.2 CdTe Homoepitaxy 327

10.3 CdTe Heteroepitaxy 327

10.3.1 InSb 327

10.3.2 Sapphire 328

10.3.3 GaAs 329

10.3.4 Silicon 330

10.4 Low‐Temperature Growth and Alternative Precursors 330

10.5 Photoassisted MOVPE 332

10.6 Plasma‐Assisted MOVPE 333

10.7 Polycrystalline MOCVD 333

10.8 In Situ Monitoring of CdTe 334

10.8.1 Mechanisms for Laser Reflectance (LR) Monitoring 335

10.9 MOCVD of CdTe for Planar Solar Cells 337

10.9.1 CdS and CdZnS Window Layers 338

10.9.2 CdTe Absorber Layer 338

10.9.3 CdCl2 Treatment Layer 342

10.9.4 Photovoltaic Planar Devices 343

10.10 Core‐Shell Nanowire Photovoltaic Devices 345

10.11 Inline MOCVD for Scaling of CdTe 347

10.12 MOCVD of CdTe for Radiation Detectors 350

References 351

11 ZnO and Related Materials 355
V. Muñoz‐Sanjosé and S.J.C. Irvine

11.1 Introduction 355

11.2 Sources for the MOCVD Growth of ZnO and Related Materials 356

11.2.1 Metalorganic Zinc Precursors 356

11.2.2 Metalorganic Cadmium Precursors 360

11.2.3 Metalorganic Magnesium Precursors 360

11.2.4 Precursors for Oxygen 361

11.2.5 Precursors for Doping 363

11.3 Substrates for the MOCVD Growth of ZnO and Related Materials 364

11.3.1 ZnO Single Crystals and ZnO Templates as Substrates 365

11.3.2 Sapphire (Al2O3) 367

11.3.3 Silicon 369

11.3.4 Glass Substrates 372

11.4 Some Techniques for the MOCVD Growth of ZnO and Related Materials 373

11.4.1 Atmospheric and Low‐Pressure Conditions in Conventional MOCVD Systems 374

11.4.2 MOCVD‐Assisted Processes 376

11.5 Crystal Growth of ZnO and Related Materials 380

11.5.1 Crystal Growth by MOCVD of ZnO Layers 380

11.5.2 Crystal Growth of ZnO Nanostructures 393

11.5.3 Crystal Growth of ZnO‐Related Materials 398

11.5.4 Doping of ZnO and Related Materials 400

11.6 Conclusions 405

Acknowledgments 406

References 406

12 Epitaxial Systems for III‐V and III‐Nitride MOVPE 423
W. Lundin and R. Talalaev

12.1 Introduction 423

12.2 Typical Engineering Solutions Inside MOVPE Tools 424

12.2.1 Gas‐Blending System 424

12.2.2 Exhaust System 433

12.2.3 Reactors 435

12.3 Reactors for MOVPE of III‐V Materials 438

12.3.1 General Features of III‐V MOVPE 438

12.3.2 From Simple Horizontal Flow to Planetary Reactors 439

12.3.3 Close‐Coupled Showerhead (CCS) Reactors 445

12.3.4 Rotating‐Disk Reactors 447

12.4 Reactors for MOVPE of III‐N Materials 451

12.4.1 Principal Differences between MOVPE of Classical III‐Vs and III‐Ns 451

12.4.2 Rotating‐Disk Reactors 454

12.4.3 Planetary Reactors 455

12.4.4 CCS Reactors 458

12.4.5 Horizontal Flow Reactors for III‐N MOVPE 459

12.5 Twenty‐Five Years of Commercially Available III‐N MOVPE Reactor Evolution 462

References 464

13 Ultrapure Metal‐Organic Precursors for MOVPE 467
D.V. Shenai‐Khatkhate

13.1 Introduction 467

13.1.1 MOVPE Precursor Classes and Impurities 468

13.2 Stringent Requirements for Suitable MOVPE Precursors 472

13.3 Synthesis and Purification Strategies for Ultrapure MOVPE Precursors 472

13.3.1 Synthetic Strategies for Ultrapure MOVPE Precursors 472

13.3.2 Purification Strategies for MOVPE Precursors 476

13.4 MOVPE Precursors for III‐V Compound Semiconductors 483

13.4.1 Group III MOVPE Precursors 483

13.4.2 Group V MOVPE Precursors 488

13.5 MOVPE Precursors for II‐VI Compound Semiconductors 493

13.5.1 Group II MOVPE Precursors 493

13.5.2 Group VI MOVPE Precursors 496

13.6 MOVPE Dopants for Compound Semiconductors 499

13.7 Environment, Health, and Safety (EHS) Aspects of MOVPE Precursors 500

13.7.1 General Aspects and Considerations 500

13.7.2 Employee and Environment Exposure Aspects 501

13.7.3 Employee and Workplace Exposure Limits 502

13.8 Conclusions and Future Trends 502

Acknowledgments 503

References 503

14 Future Aspects of MOCVD Technology for Epitaxial Growth of Semiconductors 507
T. Detchprohm, J.‐H. Ryou, X. Li, and R.D. Dupuis

14.1 Introduction – Looking Back 507

14.2 Future Equipment Development 510

14.2.1 Production MOCVD 510

14.2.2 R&D MOCVD 511

14.2.3 MOCVD for Ultrawide‐Bandgap III‐Nitrides 512

14.2.4 MOCVD for Emerging Materials 513

14.2.5 Democratization of MOCVD 514

14.3 Future Applications for MOCVD Research in Semiconductor Materials 515

14.3.1 Heteroepitaxy 515

14.3.2 Nanostructural Materials 527

14.3.3 Poly, Amorphous, and Other Materials 532

14.4 Past, Present, and Future Commercial Applications 535

14.4.1 LEDs 535

14.4.2 Lasers 536

14.4.3 OEICs 536

14.4.4 High‐Speed Electronics 536

14.4.5 High‐Power Electronics 537

14.4.6 Solar Cells 537

14.4.7 Detectors 538

14.5 Summary and Conclusions 538

Acknowledgments 539

References 539

Index 549

About the Author

Series Editors Arthur Willoughby University of Southampton, Southampton, UK Peter Capper Ex???Leonardo MW Ltd, Southampton, UK Safa Kasap University of Saskatchewan, Saskatoon, Canada

Edited by Stuart Irvine, PhD, DSc College of Engineering, Swansea University, UK Peter Capper, PhD Ex-Leonardo MW Ltd, Southampton, UK